Cannot Verify Server Identity

Error: Cannot Verify Server Identity

The Identity of "imap-mail.outlook.com" cannot be verified.

I was having this same issue as others, and I saw that some resolved this issue by deleting and reinstalling their email accounts on their Iphones/Ipads. I have fixed similar issues in the past just by changing my settings first. So I tried that first and so far it seems to have worked, and I haven't received any pop ups since. I turned off and on again 2 different mail settings (so I'm not sure which one resolved the issue). Here is the what I did:

Go to Settings> Mail> Accounts> Hotmail (mine was my hotmail account) > Mail (turn off and then on again). Second (on the same tab) I clicked on Account (under IMAP) and then SMTP (under Outgoing Mail Server) and turned off and on again smtp-mail.outlook.com (under Primary Server). I hope this helps!