Hi @Gail Quigley ,
Could this issue be reproduced on other account? If it only happened to your outlook account, the issue may be related to this account. I also have researched a lot about your issue and found a thread that mentioned the Office 365 MFA and the Apple Mail app for iOS, please kindly check if it’s also helpful to you.
If that’s invalid or you still would like to know more about it, due to here we mainly focus on general issues about Outlook desktop client, we may know little about the outlook account in Apple Mail, in order to solve your issues better, please kindly post a new thread in this forum:
https://answers.microsoft.com/en-us/msoffice/forum/msoffice_account-mso_imobile?sort=LastReplyDate&dir=Desc&tab=All&status=all&mod=&modAge=&advFil=&postedAfter=&postedBefore=&threadType=all&isFilterExpanded=false&page=1
The reason why we recommend posting appropriately is you will get the most qualified pool of respondents, and other partners who read the forums regularly can either share their knowledge or learn from your interaction with us. Thanks for your understanding and hope your question will be resolved soon.
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