Troubleshooting help for Office365 e-mail
Problem: Somebody sent me an e-mail with an attachment, and when I received it the attachment was missing.
Answer: Office365 blocks certain types of file attachments to prevent malware from spreading. A list of blocked attachment types can be found here: https://support.office.com/en-us/article/Blocked-attachments-in-Outlook-3811cddc-17c3-4279-a30c-060ba0207372#__attachment_file_types
Problem: I'm using O365 with an IMAP client, and it takes several seconds for every e-mail to successfully send.
Answer: This is expected behavior. The O365 mail environment has to interact with servers here at UR to authenticate users, and that interaction creates a delay of several seconds during the sending process. Some mail clients hide this delay so it's not obvious to users, while other mail clients don't.