Solved Outlook showing emails as unknown sender and no subject

Stevev9991 — Fri, 18 Sep 2026 09:31:09 GMT

So for a while now I was getting a lot of messages that were absolutely fine on my phone BT email client but on Outlook on my PC, showed with unknown sender and no subject.

I read all the previous stuff about only affecting POP3, wasn't that since I'm using IMAP but then I realsied I had Outlook configured against both my @talk21.com address and the associated .t21@btinternet.com address.

I removed the .t21 address from my outlook settings and 'boom' all the emails it couldn't read in my inbox instantly corrected.

Hope this maybe helps someone else configured the way I was.

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Solved Outlook showing emails as unknown sender and no subject