I followed this guide:
http://library.linode.com/email/postfix/dovecot-mysql-debian-6-squeeze

I can send locally, receive from everywhere but I still can't send from email clients such as Thunderbird.

Could I please get some guidance?

fabian

You will need to post log excerpts for us to have a chance at helping you.

A big help would be editing your postfix master.cf file and adding a '-v' switch to the 'submission' or 'smtps' entry, like so: http://derfy.net/images/linode01.png

Reload postfix (something like 'postfix reload' as root) and try to send mail again. Then pastebin the log entry (http://pastebin.linode.com/) from your mail log (/var/log/mail.log for me) in a post here and we'll try to help out.

It was all a typo!!! Thank you for the -v tip!

After restarting the postfix service (this time -v) I got a

warning: SASL authentication failure: cannot connect to saslauthd server: No such file or directory

I checked the SASL configuration and found a typo on

OPTIONS="-c -m /var/spool/postfix/var/run/saslauth -r"

missing a "d"...

It's all happiness now. Thank you, derfy.