A good way to test a smtp server, find out in the last “Linux Magazine”.

swaks

Example:

$ swaks -f root@free.fr -t <E-MAIL-ADDRESS> -s smtp.free.fr -stl
=== Trying smtp.free.fr:25...
=== Connected to smtp.free.fr.
=== response in 0.566s
<-  220 smtp1-g21.free.fr ESMTP Postfix
-> EHLO shogun8.local.thierry-jaouen.fr
=== response in 0.228s
<-  250-smtp1-g21.free.fr
<-  250-PIPELINING
<-  250-SIZE 35000000
<-  250-VRFY
<-  250-ETRN
<-  250-ENHANCEDSTATUSCODES
<-  250-8BITMIME
<-  250 DSN
 -> MAIL FROM:<root@free.fr>
=== response in 0.281s
<-  250 2.1.0 Ok
 -> RCPT TO:<E-MAIL-ADDRESS>
=== response in 0.293s
<-  250 2.1.5 Ok
 -> DATA
=== response in 0.023s
<-  354 End data with <CR><LF>.<CR><LF>
 -> Date: Thu, 15 Jun 2013 05:33:45 +0200
 -> To: <E-MAIL-ADDRESS>
 -> From: root@free.fr
 -> Subject: test Thu, 15 Jun 2013 05:33:45 +0200
 -> X-Mailer: swaks v20120320.0 jetmore.org/john/code/swaks/
 -> 
 -> This is a test mailing
 -> 
 -> .
=== response in 1.850s
<-  250 2.0.0 Ok: queued as 396596402AE
 -> QUIT
=== response in 0.025s
<-  221 2.0.0 Bye
=== Connection closed with remote host.

Replace “<E-MAIL-ADDRESS>” by a valid e-mail.