Event cancellation doesn't work right

[EitanBlumin]

When cancelling an event, I get in Outlook 365 a "not supported calendar message.ics" attachment, which cannot be opened in order to remove the event from the calendar.

[EitanBlumin]

I verified that the ICS contents are valid using a couple of online validators, and it passed validation.

I tried all the methods mentioned here:
https://stackoverflow.com/questions/27662899/outlook-365-receives-a-message-that-has-an-attachment-that-is-named-not-support

But nothing helped.

Currently, my suspicion is that this happened because I used a SendGrid account to send the event cancellation, which may have been detected as a sender other than the organizer.

I should test this on a new event created directly from a non-SendGrid account.

[EitanBlumin]

The same problem still occurs even when sending from a Gmail account, and when sending from a personal Microsoft account.

I'm currently at a loss. I have no idea why this is happening.

[bhodge34]

Not sure if you are still supporting this, but I found that changing the name of the ics file from Meeting.ics to invite.ics caused the cancel mail to work.

[EitanBlumin]

Wait, seriously? That easy? I'm gonna try this myself ASAP

[EitanBlumin]

Not sure if you are still supporting this, but I found that changing the name of the ics file from Meeting.ics to invite.ics caused the cancel mail to work.

I tried making the change but I'm still getting the same issue with the "not supported calendar message.ics" attachment.

I pushed the changes to the v2.4 branch. Are you sure about this solution?

[bhodge34]

You are correct. I was getting it to work when I was sending the invite attachment from gmail. If I send it from the SQL server to my outlook account, it is giving the same error. I will keep looking into it.

[bhodge34]

I spent a few more hours looking into this, and am unable to figure out why it isn't working. The work around that I came up with was to send an update meeting request in the distant past and set a mailbox rule to auto delete events older than x number of days. I know this won't work for everyone, but it may help some.

[EitanBlumin]

For reference, I generated a calendar invite using the native Outlook web-based interface and then cancelled it.
I captured the attached invite.ics file that arrived with the cancellation, and I'm adding it here:
invite.zip

I don't have the time to do it right now, but I should compare this file's contents to the contents generated by my CLR method, and take note of the differences. Maybe I'll find something.

[Julien22bzh]

Hi Eitan,
I hope you're doing well!
I'm taking advantage of the holidays to work on improving my invitation script. Have you had a chance to compare the invitation file sent with the native Outlook Web one?
Best regards
Ju