Ok this is a real puzzler!

I have a MacBook late 2008 Silver model and my boss has a MacBook Air, i'm using IMAP to contact are email server (exchange 2003) in the school using are external host name for the server as in email.schoolname.sch.uk as this will work from home internally and externally.

I can set his email up no problems on my mac using this external name and his username and network password to authenticate and can then subscribe to all the folder etc. however on his mac and other macs.... ive tested this, if refuses to work! It wont find the server (only using the internal server name as in servername.domainname this however means that when he leaves the site he cant access his email unless he setups a separate account for external using email.schoolname.sch.uk as mentioned above)!

Hope this makes sense so far! Now i've checked all the network and security settings on my mac against his and they match to the word other than the IP address obviously, so what the heck have I done to my mac that allows me to view all the email accounts internally and externally using the external name??

I was thinking it was to do with DNS and resolving the external name internally, is this the Aliases or CNAME (not to sure on correct terms been doing some research) however this wouldn't explain why my mac works and his doesn't for his email and all other??!

Please help me!!

Thanks

Steve