I've added my gmail account to my N900, and can successfully receive emails, however when I send they will hang out in the "Outbox" indefinitely with the status "sending". Has anyone else seen this?

Apparently it only works if the address I'm sending to is already associated with a contact. If I manually enter an address in the "To:" field, it will not send at all.

i tried

and working perfectly

i sent emails to some emails non in my contacts.

and it gone

It seems not to be a common problem/bug, becuase I've a Gmail account set up and it works nicely. Have you used the default Gmail settings? I mean, have you selected Gmail from the list of mail providers, or have you manually set a generic mail account with Gmail settings?

Check your SMTP options again and reenter the right password there again. (auth should be login, ssl protocol, port 465)

The other thing to check is that your provider is not blocking SMTP outgoing except ia their servers.

Here's the thing; it sends perfectly when I use an email address that is assigned to a contact, but fails to sent when I manually enter any email address in the To:.
I've verified my account settings against what gmail recommends (smtp server, port, login info)

I also experienced some problem with sending from G to G, contact was already at the contacts, but when i send the same message with picture attached to non Gmail address email was send perfectly

Hello,

In outgoing server change
secure connection normal tls
port :587

and must work

I wasn't able to send email from my GMail account on the N900, until I changed to the outgoing server from smtp.gmail.com to smtp.googlemail.com.

Here are my full settings:
Outgoing server (SMTP): smtp.googlemail.com
Secure authentication: Login
User name: xxxxx@gmail.com
Password: ****
Secure connection: SSL
Port: 465