Tim McMichael

Navigating the world of high availability...and occasionally sticking my head in the cloud...

Office365: POP and IMAP clients receive OWA links for calendar invitations

Office365: POP and IMAP clients receive OWA links for calendar invitations

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As you may know, Office 365 supports a number of different client protocols, including POP and IMAP and a variety of POP and IMAP clients. By default, POP or IMAP clients will be configured to use Outlook Web App (OWA) for handling calendar invitations. When these clients receive a meeting request, within the body of the invite is a link. Clicking on the link allows the user to open their mailbox via OWA so they can accept or decline the request.

 

If you are using a POP or IMAP client that is capable of handling ICAL messages, you may want to change your configuration settings so that you can get a better experience.

 

You can configure – on a per-mailbox basis – how POP and IMAP clients receive calendar appointments.  Get-CASMailbox can be used to view your current settings.

 

Get-CASMAILBOX –identity <NAME> | fl name,*pop*,*imap*

Name                                    : administrator
ExternalPopSettings                     :
InternalPopSettings                     :
PopEnabled                              : True
PopUseProtocolDefaults                  : True
PopMessagesRetrievalMimeFormat          : BestBodyFormat
PopEnableExactRFC822Size                : False
PopSuppressReadReceipt                  : False
PopForceICalForCalendarRetrievalOption  : False
ExternalImapSettings                    :
InternalImapSettings                    :
ImapEnabled                             : True
ImapUseProtocolDefaults                 : True
ImapMessagesRetrievalMimeFormat         : BestBodyFormat
ImapEnableExactRFC822Size               : False
ImapSuppressReadReceipt                 : False
ImapForceICalForCalendarRetrievalOption : False

In the above output, you can see two attributes that you need to set to True to enable iCAL support. The *ICALForCalendarRetrievalOption specifies that the client should be provided calendar appointments that are in ICAL format.

 

Also note the *UseProtocolDefaults attributes.  These must be set to False in order for any changes to *ICALForCalendarRetrievalOption to take effect.  You can use Set-CASMailbox to change these settings: 

 

Set-CASMailbox –identity <NAME> –PopUseProtocolDefaults:$FALSE –ImapUseProtocolDefaults:$FALSE –PopForceICalForCalendarRetrievalOption:$TRUE –ImapForceICalForCalendarRetrievalOption:$TRUE

 

Name                                    : administrator
ExternalPopSettings                     :
InternalPopSettings                     :
PopEnabled                              : True
PopUseProtocolDefaults                  : False
PopMessagesRetrievalMimeFormat          : BestBodyFormat
PopEnableExactRFC822Size                : False
PopSuppressReadReceipt                  : False
PopForceICalForCalendarRetrievalOption  : True
ExternalImapSettings                    :
InternalImapSettings                    :
ImapEnabled                             : True
ImapUseProtocolDefaults                 : False
ImapMessagesRetrievalMimeFormat         : BestBodyFormat
ImapEnableExactRFC822Size               : False
ImapSuppressReadReceipt                 : False
ImapForceICalForCalendarRetrievalOption : True

The settings described here are per-mailbox settings.  There is no global setting to change the default for the entire tenant. There is also no method to adjust the settings per-client.

Comments
  • Thanks, I've been looking for this for a while now in the Office 365 forums.

  • Will enabling this resolve issues pertaining to the calendar.app (OS X 10.9.2)? Assistance greatly appreciated.

  • Using Outlook 2013 sending invites and only affects when recipient using POP3 in our case. A suggestion above had helped. Thank you!

  • @Daniel...

    I'm not familiar with the application you are using so I cannot advise.

    TIMMCMIC

  • @Rad:

    Excellent - i'm glad this helped.

    TIMMCMIC

  • I came across this site when searching for the OWA link in an Outlook pop account. Could you please clarify whether this setting change needs to be undertaken by an administrator on the host, or is it a setting I as the end-user am able to make?

  • Bullshit!!!!

  • @JurgenO

    Your administrator needs to do this for you.

    Tim

  • @NeCoMuk

    Would you care to contribute something.meaningful?

    Timmcmic

  • try this for all mailboxes

    Get-Mailbox -ResultSize unlimited | Set-CASMailbox –PopUseProtocolDefaults:$FALSE –ImapUseProtocolDefaults:$FALSE –PopForceICalForCalendarRetrievalOption:$TRUE –ImapForceICalForCalendarRetrievalOption:$TRUE

  • @Pete :

    I might add a suggestion to this. When doing bulk operations like this depending on the tenant size you'll end up having powershell throttling kick in. I would commend the following to assist in avoiding this:

    Get-Mailbox -ResultSize unlimited | Set-CASMailbox –PopUseProtocolDefaults:$FALSE –ImapUseProtocolDefaults:$FALSE –PopForceICalForCalendarRetrievalOption:$TRUE –ImapForceICalForCalendarRetrievalOption:$TRUE -verbose ; start-sleep -m 500

    The -verbose allows us to see that the command continues to be processing and the start-sleep puts a 500 ms delay inbetween each set.

    You might also consider doing the get completely different from the set.

    Get-mailbox -resultsize unlimited | export-CSV
    $users=import-CSV

    foreach $users | Set-CASMailbox -identity $_.alias –PopUseProtocolDefaults:$FALSE –ImapUseProtocolDefaults:$FALSE –PopForceICalForCalendarRetrievalOption:$TRUE –ImapForceICalForCalendarRetrievalOption:$TRUE -verbose ; start-sleep -m 500

    TIMMCMIC

  • Thanks this looks like it might help. We are on office 365. What do I import to get these commands. Get_CasMailbox, and Set-CasMailbox are not valid commands on our AD server.

  • @SWILSONZ

    You have to log into your Exchange Online / Office 365 tenant via powershell.

    Several references can be found online.

    TIMMCMIC

  • @TIMMCMIC

    Thanks, a solution and a direction!

  • @SWILSONZ

    NP - if you do not find what you need let us know.

    TIMMCMIC

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