BleepingComputer.com: error message when opening emails

Hello,

I'm trying to setup an email for a coworker and we're having trouble. Sending and receiving seem to work OK but then when we try to open emails by double-clicking on them, we get an error message along the lines of "Can't open the email. Contents can't be accessed. Need to open email online." (this isn't verbatim; I don't have the error message in front of me at the moment).

He's using Outlook 2002. The mail service is with Telus (Calgary, Alberta). The incoming mail server is imap.telus.net (I read somewhere that IMAP mail servers can have problems like this).

Logging onto the server online can be done, and works, but he'd much rather use Outlook as the online webmail is a "pain in the ass" (his words).

Can anybody help please?