[bmbwealth]

Is there a working SMTP bruter? 
IP DOMAIN SMTP

[DramaKing]

There's not much, but you could try this: https://github.com/Kik449/smtpcracker. Keep in mind that it will only work with servers that use basic username/password authentication.

[NEED]

You can use THC-Hydra
Example
"hydra -S -l $email_addr -P $passwd_list -e ns -V -s 465 smtp.gmail.com smtp"