You can always tell somebody when you’re free. That part works today, on every system, with anyone. What stops at the line between two companies is the lookup, and almost every tool clash people describe is that one gap wearing different clothes. Once you see it, the fix becomes a choice about which channel to use.
- The availability grid that fills in for your colleagues is a directory feature. It goes blank for anybody outside your organization. Microsoft’s own documentation is plain about the reason, which is that an administrator at both ends has to configure the relationship.
- One object crosses every boundary there is, and has done since the format was first published in 1998. It’s the calendar invitation. Everything else in a meeting is optional, decided per account, and frequently absent, from the counter-proposal button to the response status to the formatting.
- The clash you actually run into is social rather than technical. You both have a booking page, each page reads only its own calendar, and somebody gives way.
- Four ways exist to hand somebody your availability. They differ mainly in what they ask of the person receiving it, and the most compatible one is a sentence.
You can do all of it on the tools you already have, and this piece leaves your tools where they are. What follows is what stops at the boundary, what still gets through, and how to pick a channel with no conversation about software.
What stops at the edge of your organization
Start with the one capability that disappears. It’s narrower than the frustration suggests.
Inside one company, you open a meeting and type a colleague’s name. Their week fills in as colored bars. You’re asking a directory a question, and the directory answers, because both mailboxes sit inside a system that trusts itself.
Type a client’s address into the same field and the bars stay empty. That’s the system working as designed. You’ve asked a question it has no standing to answer.
Microsoft describes what it takes to change that, and the description is the most useful paragraph in this whole subject. An organization relationship, it says, “is a one-to-one relationship between businesses to allow users in each organization to view calendar availability information.” It offers three levels of access: no access, availability time only, or free/busy including time, subject and location. Then comes the sentence that settles it. “The point is: the organization relationship must be set up at both ends for calendar availability information to be shared” (checked September 6, 2026).
Read that as a bill rather than a feature. It wants an administrator on each side, a named counterparty, and a separate configuration per relationship. For two firms in a long joint venture, that’s a sensible arrangement. For a coach with forty clients, or a consultancy that speaks to six new prospects a month, the setup cost is per relationship and it never amortizes.
Google’s side of the fence has the same shape. An administrator setting governs what a Google Workspace user may share outside the organization. Its least revealing option is “Only free/busy information (hide event details),” and that one lets an outsider “check when your calendar is booked and when it has free time, but not the names or details of your events” (checked September 6, 2026). The direct Google-to-Microsoft bridge, Calendar Interop, is an administrator’s job too. Google announced on May 29, 2025 that it can now be enabled through the Microsoft Graph API, replacing Exchange Web Services, “which will no longer be supported by Microsoft beginning October 1, 2026” (checked September 6, 2026).
Every route to a genuine cross-organization lookup lands on an administrator, on both sides, arranged per counterparty. One of them is mid-migration this fall. So the bridge suits two firms with an IT department at each end, and the rest of this is about the channels that work without one.
The three things “share my availability” can mean
The phrase covers three different transactions. Most of the confusion in this subject is two people negotiating one while meaning another.
Granting standing visibility. A permission on an account, letting a named person see your busy blocks whenever they look. It’s live and it lasts. It wants an account relationship, sometimes an administrator, and a setup once per person. That’s the right instrument for a business partner, a shared assistant, or a spouse. For a client it’s the wrong instrument, and it’s the one people reach for first.
Publishing it. A page anyone with a browser can open, showing bookable times, with the far end needing no account at all. It’s live, and it scales to any number of people. It asks them to use your tool, which is a small ask that occasionally lands as a large one.
Stating it. Three times in a message, or an invitation for one of them. A snapshot rather than a live answer. It asks the other person for nothing at all, works with every system that has ever existed, and holds up to a few exchanges a week.
The second and third survive contact with a stranger, and the third survives everything. So when somebody says “we’re on different systems,” move down the list. Stop at the first channel that works whatever they run.
The one object that crosses everything
The calendar invitation works where everything else stops, and the reason is worth knowing rather than trusting.
Calendar data has a published standard. RFC 5545 defines iCalendar, and its abstract states the aim in one clause that does all the work here. It’s a format “for representing and exchanging calendaring and scheduling information such as events, to-dos, journal entries, and free/busy information, independent of any particular calendar service or protocol.” Two companion specifications carry it. RFC 5546 defines the scheduling protocol on top of it, “to provide scheduling interoperability between different calendaring systems.” RFC 6047 binds that protocol to ordinary email.
So when you send an invitation to somebody on the other platform, you’re sending a standards object over email. Both products read it, because both were built to. The .ics file at the bottom of the message is that interchange format, doing the job it was first published to do in November 1998, as RFC 2445.
That’s why, across a boundary, “send the invitation” beats “share the calendar” nearly every time. One is a standard. The other is a permission.
The standard also holds something the products left out. RFC 5545 defines a free/busy component, VFREEBUSY, whose purpose is stated as “To publish busy time information.” It covers asking for somebody’s availability, replying with it, and publishing it unprompted. A machine-readable way to hand a stranger your free hours has existed for a quarter of a century. The mail clients most people use leave it without a button.
That gap is the whole explanation for why the practical answer is prose. The format solved this. The products shipped the events and skipped the availability, so what reaches the other person is a meeting or a sentence.
Getting the inside of the invitation right, so it settles the matter in one pass, is a craft in itself. It’s covered in writing a calendar invitation that arrives complete.
What survives the crossing, and what arrives as decoration
Six things reach the other side intact. The start time, the end time, the title, the location or video link, the attendee list, and whatever you typed in the description. Treat the rest as best-effort, and hold your plan to those six.
The counter-proposal is the biggest one. RFC 5546 has carried a method for negotiating a change to a proposed time since 2009. What that mechanism is, and why people reach past it for prose anyway, is set out in catching a reschedule request buried in a reply. The part that belongs here is narrower and less discussed. Whether the control appears at all is a property of the recipient’s account rather than of the meeting. Microsoft’s page for the feature states that “this feature is only available for work or school accounts. Microsoft accounts using outlook.com, hotmail.com, live.com, and msn.com addresses, as well as IMAP or POP accounts from another provider are not supported” (checked September 6, 2026). Google, on the other side of the fence, announced on July 30, 2018 that its own version “works across domains and with Microsoft Exchange.”
Put those together. A single meeting shows one attendee a tidy propose-a-new-time button and shows the other a plain invitation, on the basis of which kind of mailbox each of them signed up for. Each person sees only their own screen. So silence might mean declined, missed, or a control that never rendered.
The response status is unreliable across the line. Somebody who accepted days ago sometimes shows as silent on your side. Let it sit. When you want to know whether they’re coming, ask in a sentence and read the reply.
Formatting can eat the invitation outright. Microsoft documents that Outlook’s Rich Text format uses Transport Neutral Encapsulation Format. Its page says “recipient messaging systems that aren’t based on Microsoft Exchange might not be able to interpret messages that use this TNEF format. If the recipient’s messaging system can’t process this format, a file attachment that’s named Winmail.dat is added to the message.” The same page then notes that “some Outlook features require TNEF. These include meeting requests and responses” (both checked September 6, 2026). There’s the trap in one line. The encoding that makes an Outlook meeting request work is the encoding a non-Exchange recipient may fail to open. When a client tells you your invitation arrived as an unreadable winmail.dat, the cause sits on the sending side, and the message format governs it.
Recurring series are the most fragile thing that crosses. A whole series usually lands. An edit to one occurrence of it is where cross-platform behavior gets strange, and both ends stay quiet about it. Where a series matters, say what changed in words as well as changing it.
One rule falls out of all of this, and it’s the rule to keep. Anything the other person has to click inside an invitation is a maybe. Anything you wrote as words is a certainty. So the load-bearing information goes in the sentence rather than the field. Give the time in full and the zone spelled out. Say what the meeting is for. Add one line telling them how to move it.
Writing the hour itself so that a misreading announces rather than hides itself is a discipline of its own. It’s worked through in scheduling across time zones.
When you both have a booking page
Here’s the clash people actually mean, and it’s a social one.
You have a page. They have a page. Each page reads only its own calendar, so the second one adds nothing. Send yours while they send theirs, and what you’ve exchanged is two invitations to do the arranging. A plain list of times would have put you closer to a meeting, and both of you walk away thinking it’s settled.
Whether a link is the right instrument in the first place, and the relationships where sending one is a small insult, is settled in booking links that show real availability. What’s specific to a clash is the tie-break. Both of you have a page, both of you are entitled to send it, and somebody gives way.
Yield in this order.
Whoever wants the meeting more uses the other’s page. It’s the same test that decides whether sending a link was polite, and it settles most cases before you’ve thought about it. If you approached them, their page. If they approached you, yours.
If it’s genuinely mutual, the side with more people yields to the side with one. A booking page is one-to-one by construction. Two people on your side need to be there, you take a slot on their page, and you’ve committed a colleague on their behalf. Unwinding that costs more than the minute it saved.
If it’s still tied, whoever received a link first uses it. The rule is arbitrary, and that’s the point. Any rule at all beats a negotiation about software, which is a conversation that ends badly however it goes.
Then close it in one line, and skip the meta-conversation.
Booked you for Thursday at 10:30 Eastern, easiest to just use yours.
One line, no discussion of tools, and the minute it cost you is a minute you were going to spend anyway. Replying to a link with a link is the move to leave alone. However you phrase it, it reads as a refusal to be the one who bends, and the other person reads it that way whatever you meant by it.
Two practical notes on this.
A booking page is a web page. You can take a slot on somebody’s page whatever you run yourself, because taking a slot means opening a link and typing your name. “I don’t use that one” is usually about who yields, which is a fair thing to feel and a different thing to say.
And the failure that actually costs money is taking a slot on their page while your own availability sits unreconciled, so you’ve booked against a calendar that knows nothing about Thursday afternoon. That’s the subject of reconciling two calendars without keeping a third, and it’s worth fixing before you get comfortable clicking on other people’s pages.
Four ways to hand somebody your availability
Ranked by what they ask of the person on the other end. Pick the lowest one that answers the question in front of you. Capability rises as you go down the list, and reliability falls.
Named times in the message. Asks nothing. It works for the client on a phone in a parking lot, the one whose employer blocks scheduling domains, and the one who has never opened a calendar application in their life. It’s a snapshot, true at the moment you typed it, and it holds up to around a handful of exchanges a week. This is the default, and the one people underrate most.
Two that work my end: Tuesday the 15th at 2pm, or Wednesday the 16th at 9:30, both US Eastern. Say which and the invitation goes out today.
Two details in there are doing the crossing. The zone is written in words rather than left to the reader’s software. And the message promises an invitation, which is the object that arrives intact on whatever they’re running.
A calendar invitation. Also asks nothing, and it carries a decision rather than an offer. The format is what takes it across every boundary, all on its own, with no relationship between your company and theirs. Use it when you already know enough to act. Add one line saying you’re proposing rather than deciding, and that a change is theirs for the asking. A meeting request with a sentence around it is the single most reliable object in this entire subject.
A published page. Asks for a browser and a willingness to use your tool. In exchange it’s live, so it stays current between the writing and the reading, and it scales to any number of people. Leave it aside for group scheduling and for anyone who is doing you a favor.
A standing sharing permission. Asks for an account on a compatible platform, usually an administrator’s blessing on one or both sides, and a setup per person that only pays itself back across a short list. Genuinely right for a business partner, a shared assistant, or a client engagement where you hold a seat on their system anyway.
There’s a half-step some people reach for, and it’s worth being honest about. You can attach an .ics file to a message rather than sending a proper invitation, and every mainstream calendar will open it. What you get is an attachment rather than a meeting request. It arrives as a file to be noticed and clicked, with no attendee list and no response coming back to you. It’s a decent way to hand somebody a hold you’re happy for them to ignore. As a substitute for either of the two channels above it, it’s poor, and it still needs the sentence.
One more route looks like the obvious answer and carries a cost worth knowing first. Making your calendar publicly subscribable gives somebody on another platform a live feed, and Google’s help page is clear about the condition attached: “the iCal address only works if the calendar is public” (checked September 6, 2026). Public means public to the internet, indexable, permanent, and out of your hands once shared. For a practice holding client names in event titles, that is not a sharing setting. It is a disclosure, and it belongs in the same category of decision as the rest of using an AI inbox without breaking confidentiality.
When the link is theirs and the constraint is yours
Most of this subject is written from the sending side. The receiving side has its own set of small problems, and each has a short answer.
None of the offered times work. Reply with what does. A booking page is an offer, and the person behind it will nearly always take an emailed time. You’re free to settle this on your own terms.
The page offers times you would rather leave alone. A call at 8:00, a Friday afternoon, the fourth session in one day. A page holds gaps rather than preferences, so it sells whatever your correspondent’s calendar left empty, regardless of what their week is really like. Take a different slot or name one. Your own page has the same limitation, and it’s dealt with in booking links.
The confirmation lands somewhere you never look. This is the quiet one. A booking made on somebody else’s page writes the event to their calendar and sends you an invitation by mail. When that mailbox belongs to a different calendar from the one you actually consult, the meeting sits in their week and stays out of yours, and you find out on the morning. Check where it landed the first time you use anyone’s page, rather than the fifth.
Your own week is out of sight while you pick. Choosing a slot on a web page means choosing with your calendar somewhere else, which is exactly the condition that produces double bookings. Open your calendar in another tab before you click, or check within the hour. The correction is yours to make from there, and it’s moving a meeting rather than a quick note.
Your network blocks the page. Uncommon but real, particularly in health care, finance and government. Say so plainly and offer times. It’s a fact about somebody else’s firewall, and it reads as one.
What matching tools would not fix
Knowing the edges here saves more time than another tactic.
Policy on their side. Plenty of organizations forbid external calendar sharing outright, and your own settings stop at the edge of their tenant. When somebody tells you they can’t share their calendar, believe them. It’s usually true, and it’s usually somebody else’s decision.
A calendar that was wrong before it crossed. Interoperability transmits a bad answer as faithfully as a good one. If the times you publish include the morning you’re at a conference, matching tools with your client just speeds the error on its way.
Somebody else holding the pen. As soon as an executive assistant or an office manager appears in the thread, you’re in a negotiation rather than a lookup. Different moves apply, and ending the meeting scheduling back-and-forth covers what to send and what to expect.
More than two people. Each additional attendee raises the chance that one of them sits on a system the others can’t see, and the shape of the problem changes from a lookup to a search. The move that works there is asking for conflicts rather than agreements, which is in the same guide.
A person who keeps no calendar. Common enough to plan for, particularly among older clients and in the trades. Availability sharing means nothing at all in that relationship. A phone call and a confirmation email is the entire protocol, and it works.
And the case where something else genuinely fits better, said once. Some people you schedule with every week. A co-director, a shared assistant, a year-long engagement where you already hold a seat on the client’s system. There the standing permission is worth its setup, because hundreds of lookups amortize it. Set it up and skip the rest of this. The moment the list of counterparties runs past a handful of names, that arithmetic reverses and the channels above are cheaper every time.
Answering the availability question inside the message
Everything above narrows to one instruction. Use the channel that works whatever the other person runs. Point is an email client sitting on top of the mailbox you already have at Google or Microsoft, and it works in that channel, because the thread and the calendar are one surface rather than two applications you hold in your head at once.
Point checks and reconciles the calendars you keep before proposing anything. So the hours that leave in a reply clear all of them, rather than the one that happened to be open. Point then runs the exchange in real times, written into the message in ordinary words, which is the one route an administrator on the far side leaves alone. Whatever comes back, Point reads in the words the other person chose. That includes a request to move something buried halfway down a message about an invoice, which is precisely what a counter-proposal turns into once it has crossed a boundary. You approve the time that’s settled. Your approval is what puts the invitation out with everyone on it and the event in your calendar. It lands on their platform for the reason this piece has been making since the middle: an invitation is a standard, not a favor between two vendors. Where a page fits the job better, the page publishes the same reconciled hours.
Operating more than one business keeps them apart. Each card says which one it belongs to, a single switch narrows the whole app to one, and mail goes out from the address that matches.
Three things worth having straight before you decide.
Point works with the visibility you have been granted. Your client’s calendar stays unreadable to Point, and no product is going to negotiate an organization relationship with their IT department. What disappears is your half: the looking, the drafting, the typing out of hours, the waiting to notice a reply. Those are the hours this costs you.
Judgment is still yours to supply. Which client is worth the good slot, and that your day starts at 10:00, are things Point holds once somebody has written them down.
Scheduling also has its own position on the autonomy dial, held separately from every other kind of action Point takes. Out of the box it sits on review. A proposed time and a drafted invitation are both shown to you first. Move it up when a run of threads has gone the way you would have sent them yourself, and at the far end the exchange is simply handled. Setting how much your inbox does on its own goes position by position, and undoing what Point did explains the record that makes an undo possible, along with where it runs out. A client already holding your meeting in their own calendar gets a cancellation, which is a second message rather than the erasure of the first. For the other nine tenths of a mailbox, benefits.
Common questions
How do I share my availability with someone who uses Outlook when I use Google Calendar?
Write the times in the message. Three real slots, with the date, the hour and the time zone spelled out in words. That reaches an Outlook user, an Apple Mail user and somebody reading on a phone in a parking lot, because plain text is the one channel with no compatibility surface at all. When a time is agreed, send a calendar invitation rather than another message. An invitation is a standards object defined by RFC 5545 and delivered over ordinary email. That’s why it lands correctly on the other platform, whatever the relationship between your company and theirs.
Why is the scheduling assistant blank for people outside my company?
Because free/busy lookup is a directory feature, and the directory answers only for the mailboxes inside it. Microsoft’s documentation describes what would change that: an organization relationship, which is “a one-to-one relationship between businesses,” and which “must be set up at both ends for calendar availability information to be shared” (checked September 6, 2026). That means an administrator on each side, configured per counterparty. It’s a reasonable arrangement between two firms in a standing partnership, and a poor fit for anyone with a long client list.
Can I share my calendar with someone who does not use the same system as me?
Two routes work, and both start on your side. Publish a bookable page, which anyone with a browser can open. Or state the times in a message, which anyone at all can read. A live permission is the one that usually stops, because permissions are granted to accounts on a platform. Making the calendar itself publicly subscribable is a third option and usually the wrong one for a practice. Google’s help page notes that a calendar’s iCal address “only works if the calendar is public” (checked September 6, 2026), and public means published to the internet with client names in the event titles.
We both sent each other booking links. Who gives way?
Whoever wants the meeting more takes the other’s page. It’s the same test that decides whether sending a link was polite in the first place. If that’s genuinely even, the side with more attendees yields to the side with one, because a page books one person and would commit your colleague on their behalf. If it’s still tied, use whichever link arrived first. Then say so in one line and move on, because any rule beats a conversation about software.
Why did my meeting invitation arrive as a winmail.dat file?
Because it was sent in Rich Text format. Microsoft documents that this format packages the message using TNEF. Its page says “recipient messaging systems that aren’t based on Microsoft Exchange might not be able to interpret” it, and that when they can’t, “a file attachment that’s named Winmail.dat is added to the message” (checked September 6, 2026). The awkward part is that the same page lists meeting requests among the features that require TNEF. The fix sits on the sending side rather than yours, in composing with HTML or plain text instead, and Microsoft’s own troubleshooting page documents the setting that controls it.
Why can I not propose a new time for a meeting?
Because the control depends on your account type rather than on the meeting. Microsoft states that the feature “is only available for work or school accounts.” It adds that consumer Microsoft addresses “as well as IMAP or POP accounts from another provider are not supported” (checked September 6, 2026). Google announced in July 2018 that its equivalent “works across domains and with Microsoft Exchange.” So two people in the same meeting can have different buttons. Where the button is missing, reply with the time you want in a sentence, which is what most people do anyway.
Is there one calendar format that everything reads?
Yes. iCalendar, defined in RFC 5545, is a format for calendaring and scheduling information “independent of any particular calendar service or protocol.” RFC 6047 binds the scheduling protocol built on it to ordinary email. That’s what the .ics attachment on a meeting request is, and it’s why invitations cross platforms reliably where permissions stop. The same standard also defines a component for publishing free/busy time, which is the part the products largely left without an interface.
The short version
What breaks between two organizations is narrow. You can’t look each other up. The availability grid is a directory feature, and getting it to work across a boundary takes an administrator on both sides, configured per counterparty. That’s fine for a standing partnership and pointless for a client list.
What still crosses is the calendar invitation, because it’s a published standard carried over email rather than a favor between two platforms. Around it, treat everything optional as optional: the counter-proposal button depends on the recipient’s account type, the response status is unreliable, and Rich Text can turn the whole invitation into an unreadable attachment. Put the load-bearing detail in words, where it survives.
So pick the channel that asks least. Named times in a message work with everyone. An invitation works with everyone and carries a decision. A page is live and scales, and it asks them to use your tool. When you both have one, whoever wants the meeting more gives way in a single line rather than negotiating. A standing permission earns its setup for the handful of people you schedule with every week.
A coaching practice booking the same clients on their own phones lives on the first two. A consultancy sitting on two client tenants will meet every problem in this piece in a normal month, and it’s the case where holding a seat on the client’s system genuinely pays. Everyone else in the trades this is built for sits somewhere on that spread, and one sentence covers all of them: the most compatible thing you can send is the thing you typed.