I've always used 465, which is the port Gmail specify in their help pages.
Not only did it take ages to get going, as mentioned in the link above (but presumably, this is only once), but then when I closed it it spent a ridiculous time on some housekeeping - same again when I tried a second time.
I was just having a look out of curiosity (I use alpine), but if I were to have another go, I would try port 465 for SMTP as suggested by djemos. Though it's probably not that that was slowing it down. Maybe, indeed, that too was a one-off process triggered by my sending an email.
![Smile :)](./images/smilies/icon_e_smile.gif)
I've got quite a bit of mail in my Gmail account - Claws took a long time to build the mail tree, but is quite fast once that is done.
The only thing lacking in the Salix version is HTML rendering. I get too much HTML mail, mainly commercial in nature, so I'll have to see if I can build the HTML plugin for it. If that works, I'll give Claws a try for a while. Be interesting to see how well it works compared to the Seamonkey email client.
Paul.