Cannot send email on iPhone 7

Settings, Mail, Accounts.

Delete the offending account.

Add it back.

If that does not help come back with the error message details.

https://discussions.apple.com/thread/252457920

If you are British, AOL are changing from .com accounts to .co.uk and restricting some mail clients access

Check AOL support.

Cannot send emails on iPhone 8 after recent update. Deleted email reset it up but no good. Gone into settings checked all ok, reput passwords etc but to good. Says invalid address for sender. Sometimes it says no password for aol.