I want to build a simple email server on vps with no any ssl certification.
AFTER master the simple email server , I want to build a email server on vps with ssl certification.Here is the way to do it:
apt-get install postfix dovecot-imapd dovecot-pop3d

My domain is noxp.info , email account is joe@noxp.info , passwd for the email is "itisatest" , you can ssh the account and test to send and receive emails, it is ok.

joe@born:~$ cat /etc/postfix/main.cf
smtpdbanner = $myhostname ESMTP $mailname (Debian/GNU)
biff = no
appenddotmydomain = no
readmedirectory = no
myhostname = born
aliasmaps = hash:/etc/aliases
aliasdatabase = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = noxp.info, born, localhost.localdomain, localhost
relayhost =
mynetworks = 127.0.0.0/8 [::ffff:127.0.0.0]/104 [::1]/128
mailboxsizelimit = 0
recipientdelimiter = +
inet_interfaces = all

It seems to me that everything is in good order.
But i am confused that the email server can't connect by thunderbird.

Please try all of them.

How to fix it ?Thank for your answer.