I've set up my Lineone email on my iPhone. Receive works just fine but I cannot send emails. All the settings are correct (as verified by using information on the Talk Talk site - https://help2.talktalk.co.uk/email-settings-imap-pop3) but I just get an error message saying that the log in email address was rejected by the server.
Do I need to change the settings and use a relay server because it's two different networks trying to communicate or does it sound more like an issue with Talk Talk?
Talk Talk helpfully forgot to mention in their help pages that you must add your email address and password to the SMTP settings, implying that as you've already entered them for the IMAP settings that you don't need to.
Now I've got that sorted I can send emails to my heart's content!