BlueMail Calendar for Exchange and Microsoft 365

An invitation is an email right up to the moment you accept it, and then it is a commitment. Any client that makes you change applications between those two states has misunderstood the job.

Answering in place

When an invitation arrives, BlueMail shows it as what it is. Accept, decline or propose a new time from the message itself, and see what you have already committed to in that slot before you answer.

That last part is the one that prevents double bookings. Answering an invitation without seeing the surrounding day is guessing.

Your response propagates back to the organizer through the same channel it arrived on, so their attendee list updates without a separate reply.

Connecting properly

For Exchange, Microsoft 365 or any tenant using ActiveSync, add the account as Exchange rather than IMAP. Mail, calendar and contacts then travel over one connection with server-driven push.

This is worth repeating because it is the single most common configuration mistake. IMAP carries mail and nothing else. An Exchange account added as IMAP will never show a calendar, no matter how long you wait or how many times you reinstall.

Free and busy

Where your organization publishes availability, BlueMail reads it, so when you are scheduling you can see who is actually free rather than sending an invitation into a void and waiting.

Availability is only as good as the calendars behind it. If half your colleagues keep their real commitments in a private calendar, no client can fix that.

Recurrence, exceptions and time zones

The three things that break calendars, in order:

Recurrence rules. Every Tuesday, the first Monday of the month, every other Thursday except in August. BlueMail syncs the rule rather than expanding it into hundreds of separate events, so a change to the series is one change.

Exceptions. The one week the standup moved. Exceptions ride along with the series and stay attached to it.

Time zones. Events carry the zone they were created in, not a fixed offset. This is the difference between a recurring meeting that stays at 09:00 local for everyone and one that silently shifts by an hour twice a year when daylight saving changes in one country but not another.

If you have ever watched a global standup drift, you have watched a client that stored offsets.

Practical notes

• Multiple calendars, one view. Work, personal and shared calendars overlay in a single week, color coded by account
• Reminders follow the event, so an alert set on the desktop fires on the phone
• Offline reading works from the local cache; changes queue and send when the connection returns

For calendars outside the Exchange world, see calendar integration beyond Exchange, and for what happens on the wire, how sync actually works.