Mail on iPhone -can't verify details?

Mail on iPhone -can't verify details?

Hi I am trying to set the mail up on my iPhone and it keeps telling me it can't authenticate. I have 4 different emails all xxx@mydomain .co.uk

I set the first one up and it is working ok. However I can't seem to get any of the others to do so! I have ensured they are IMAP enabled

Help?! Thanks!