I don't think Gmail settings can entirely solve your problem even as of today.

See brutish workaround at the bottom of this link that might help with SSL issue on some servers (or might not) but worth a try perhaps:

http://community.activestate.com/node/10130

One other devil in the Gmail details is what Google calls "adaptive spam filtering" which we faced. When SMTPing blast of emails using Gmail SMTP directly, that caused a varying number of emails to send properly, but the remainder of our maillist got clipped/truncated because of this Gmail feature.

We eventually had to set up our own SMTP server to avoid sending through Gmail's SMTP, but we included our real Gmail address as the Reply-To header so any responses came back where we wanted them!

Hope this helps or inspires other ideas!

Larry