A quick summary of the correct set up for mail.coop users (using the example ‘testacc@myphone.coop’).
Make sure you enter your new mail.coop password. This will be the four-word-pass-phrase that we sent you, unless you have since changed it.
Again, use your new mail.coop password. Note that the incoming mail server is mail.mail.coop – not imap.myphone.coop or similar.
Again, use your new mail.coop password. Note that the outgoing mail server is mail.mail.coop – not smtp.myphone.coop or similar.