ERROR MESSAGE - THE USER NAME OR PASSWORD FOR _____ IS INCORRECT

I had this problem today and have had it before. To be clear the problem was that although my iphone6 had been connecting to my IMAP/SMTP mail (at Go Daddy) with no problems it suddenly stated reporting incorrect username or password on send only - receive worked fine.

The first time (a couple of months ago) I had the problem I changed the password at my provider end and then changed it on my phone and that (this took a couple of days) seemed to fix the problem.

When it happened today I decided to try to find another route and this time change my smtp server to use SSL and the port to 465. This fixed it immediately - hope this might help someone else.

If Mail has been working correctly previously and you haven't changed any setting or connected to a different router, the cause of the message is usually related to a problem with the email provider.