lucesem

The following is assuming you're using O365; please correct me if I'm wrong.

Yes, make sure you upgrade to v1.17.4 (or v1.18) and install the latest build of the OAuth2 plugin from our website before proceeding.

The key difference with O365 Shared Mailboxes is that you have to either use a Global Admin to consent on behalf of the shared mailbox -or- you can use really any account with read/send permissions for the shared mailbox. Best practice is a an account that's not a global admin so your global admin isn't tied to it in any way.

To add read/send permissions go to the Admin Center (not EAC just AC), expand the Teams and Groups tab, click the Shared Mailboxes tab, search for the Shared Mailbox, and click the name of the mailbox to bring up the Edit blade. Then you can scroll to the Manage Mailbox Permissions section and add any account that you want to authorize on behalf of the Shared Mailbox in the "Read and manage permissions" and "Send as permissions" options. This effectively lets the chosen account read and send mail from the shared mailbox.

Once you either have a Global Admin account or another account setup with appropriate read/send permissions then you can add the shared mailbox in osTicket under Admin Panel > Emails > Emails. After you've done that you can follow this guide to configure Modern Authentication. Keep in mind, when it brings you to O365 to login you must login as the account that has read/send permissions to the shared mailbox; this is important.

Please note, there is another important difference here and that's when you click Config to open the Authentication popup, on the first tab you need to uncheck the box for Strict Matching. Unchecking the box will allow another account to authorize on behalf of the shared mailbox. If you leave this box checked then you will only be able to authorize as the shared mailbox which you can't do as it doesn't have it's own login credentials. Also, you may need to uncheck the box and submit the popup twice as sometimes the box doesn't save first try. So if you get an error about a mismatching email just click Config again, uncheck the box, and re-submit the popup.

Cheers.