In reply to a post by Anonymous:Finally sussed it....
The tip is to disregard the advice given on the "3" website regarding altering smtp port numbers.
These are the settings that work for me on a "3" dongle in the UK as of Dec 20th 2009...
This is for OUTGOING mail ONLY!!
smtp server = smtp-mbb.three.co.uk
Port Number = 25 (default)
No authentication required
No secure connection required
Voila - Bob`s yer lobster
Hope this helps Si
this works using talktalk email address and Thunderbird also. Great help, thanks