I'm having a similar problem but in Outlook. For the last 3 days I cannot get my telus.net and the box asking for imap.telus.net username and password keeps coming back every 5-10 seconds. I try to retype my password to no avail. I'm tempted to delete the added e-mail in Outlook but I'm worried about losing any information.
Looking forward to hearing if anyone has an answer for you so I can apply it to my circumstances.