@clydesdale
first set up accounts using IMAP protocol (not POP3)
try creating a new password for the e-mail account
then delete the account on the iPhone and recreate it with the new pwd
this may solve the problem on the iPhone
also change the pwd on iPad/MacBook and other mailboxes
otherwise follow @Doremi advice
For anyone with an iPhone or iPad, instead of checking your e-mails via webmail in the Safari browser, which causes problems (as mentioned on this forum),..." there's a native application on your iPhone or iPad called 'Mail', which is much more user-friendly. On the app, everything is much more legible, and many options are available, such as adjusting text size or displaying bold characters. What's more, it's quick and easy to delete several e-mails at once. Best regards Doremi