How to schedule with clients and candidates outside your company (whose calendar you can't see)

Inside your organization, Outlook can show you when colleagues are free. The moment the other person is a client, a candidate, a partner or a vendor, that stops: their free/busy isn't visible to you, and yours isn't visible to them. Scheduling becomes an email exchange — and the way you run that exchange decides whether it takes one message or six.

The pattern that works

Do the hard part on your side, once. Merge every internal calendar that needs to be in the meeting, pick a window (next two weeks is the sweet spot), convert to the other person's timezone, and send the resulting list with a one-line "pick any of these". They are choosing from certain-to-work times, so the reply is a single line and the invite goes out the same day.

Timezone first, always

State the timezone once at the top of the list, in their zone if you know it. "10am" without a zone is the single most common cause of a missed external meeting. If you are unsure of their zone, say yours explicitly and offer a wider spread of times.

When to use a booking link instead

Booking links are great for inbound, high-volume scheduling (demos, office hours). For a specific client or a candidate you are courting, offering times in the email itself reads as more personal — and it keeps the meeting inside a conversation they already have open.

Why the calendars go dark at the org boundary

It is worth understanding the mechanism, because it explains which workarounds are real and which are wishful. Free/busy is published inside a Microsoft 365 organization by default — that is why your colleagues appear instantly. Across organizations it is not, unless two sets of administrators have deliberately set up an organization relationship between the tenants, or the individual has shared their calendar with you directly.

Both of those exist and both are slow. An organization relationship is a project between two IT departments, sensible for a long-running partnership and absurd for a sales call next Tuesday. An individual share is a favour you have to ask for, and asking a candidate to share their calendar with you before a first interview is not a thing anyone does. For a meeting that needs to happen this week, the answer is not to obtain their availability — it is to supply yours.

The two-week window, and why it is the sweet spot

Too short and a single conflict on their side sends the whole exchange back to the start. Too long and the times at the far end are not real: a slot twenty-five days out has a good chance of being taken by the time they reply, which turns your careful list into an apology. Two weeks is far enough to absorb one round of "none of those work" and near enough that the slots survive the reply.

The exception is the deliberately distant meeting — a quarterly review, a board date, an onboarding session six weeks out. There the point is to claim the time before anyone else does, and a sixty-day window is the right tool. Just send those with an explicit "I'll hold these until Friday", because a list that far out is a promise about a calendar you do not fully control.

Making the list

OpenSlot merges your internal calendars and outputs the paste-ready list in any timezone, so the "send a few times" step takes one click instead of a calendar scan. Example:

All times in US/Eastern
• Today 07/08
  03:30 PM - 04:00 PM
  05:00 PM - 05:30 PM
• Thursday 07/09
  09:30 AM - 10:30 AM
  12:00 PM - 01:00 PM
  02:30 PM - 03:00 PM

Every constraint that matters is applied before you see it: only times when all of your side is free, only inside working hours, only blocks long enough to hold the meeting, and all of it expressed in their zone rather than yours. The external person receives dates and times and nothing else — no page to visit, no account to create, and nothing about your internal calendars beyond the gaps you chose to offer.

Common questions