Can't get MAIl to connect to Onetel server

Question

Both my wife's (MacBook) and my IMac will not connect to the Onetel POP outgoing server - we get error message
+OK rslrimap1msp  All emails need to go out using gmail or MobileMe. The incoming is OK.
It has not always been this way only in the past year and I wonder if it is a problem with upgrading software. If I use WebMail it is OK and Onetel have checked everything and say that there is nothing they can do - very frustrating.
I have recently upgraded to OS 10.7.3 but this has not solved the problem. Is there anyway that I can reload MAIL? - or is there any other solution. The settings work prefect on our iphone.

Answer 1

Please follow these directions to delete the Mail "sandbox" folder.
Back up all data.
Triple-click the line below on this page to select it:
~/Library/Containers/com.apple.mail
Right-click or control-click the highlighted line and select
Services ▹ Reveal
from the contextual menu.* A Finder window should open with a folder named "com.apple.mail" selected. If it does, move the selected folder — not just its contents — to the Desktop. Leave the Finder window open for now.
Log out and log back in. Launch Mail and test. If the problem is resolved, you may have to recreate some of your Mail settings. You can then delete the folder you moved and close the Finder window. If you still have the problem, quit Mail again and put the folder back where it was, overwriting the one that may have been created in its place. Post your results.
Caution: If you change any of the contents of the sandbox, but leave the folder itself in place, Mail may crash or not launch at all. Deleting the whole sandbox will cause it to be rebuilt automatically.
*If you don't see the contextual menu item, copy the selected text to the Clipboard (command-C). In the Finder, select
Go ▹ Go to Folder...
from the menu bar, paste into the box that opens (command-V). You won't see what you pasted because a line break is included. Press return.