For the record, I had similar issues -- my smtp settings worked fine using a command-line utility on my windows7 box (starttls, authentication, port, hostname, it was all correct), but, when I took this info to my n900, connected to the same network by WiFi, it suddenly would not send. It said it could not contact the mail server and to please make sure my network had connectivity....

As it turns out, re-doing the settings and re-starting Modest fixed the problem -- my conclusion, if you change ANY settings in Modest, restart it to be sure the changes actually take effect.

I hope this helps.

Cheers!
Joshua

Just about the only thing Modest improved on vs osso-mail was the imap support (tho even that may be heavily biased toward the messed up Gmail implementation of such). The rest seems to have stayed still or regressed.

Have you tried using claws? I can send through gmail with claws but not modest, so I just gave up on modest.