Activating SMTP Authentication To Other Mail Servers (Postfix)

Support knowledgebase (rsimai_imap_smtp_auth)
Applies to

eMail Server: Version 3

Situation

You want to activate SMTP-AUTH so the eMail Server can authenticate itself as a client to another mail server. Although the following description mainly refers to the eMail Server 3, it should also work with the standard distribution if Postfix is used as MTA. A description for sendmail is available here

Why SMTP-AUTH

Nowadays, many ISPs have opted to accept e-mails only from clients that have previously authenticated themselves to the server. The reason for this is that it is very difficult to monitor who sends messages to whom in dial-up connections. The increase of SPAM messages makes it necessary to check if the sender is authorized. 'pop before smtp', which allows the sender to use the provider's SMTP server during a given period of time after an authenticated POP call, is often used for these purposes. The problem mostly arises when the eMail Server is temporarily connected to the Internet -- without a dedicated line and static IP address.

Prerequisite

Postfix is already installed and configured on your system. Your ISP has already supplied you with a user name and password that can be used for the server authentication via SMTP. Since this is not normal procedure, we recommend you ask your provider if you can use SMTP-AUTH.

Procedure

  1. Make sure the following entries are available in /etc/postfix/main.cf or insert them if this is not the case:
    smtp_sasl_auth_enable = yes
    smtp_sasl_security_options = noanonymous
    smtp_sasl_password_maps = hash:/etc/postfix/saslpasswd
    
  2. Create a file called /etc/postfix/saslpasswd with the following content:
    destination      username:password
    
    destination usually refers to the relay host you use. With this, instruct Postfix to deliver via SMTP-AUTH (to the possible extent) all messages transported through the specified host. Other possible routes will be dealt with as before.
  3. Finally, generate the new map and reload the configuration:
    postmap /etc/postfix/saslpasswd
    rcpostfix reload
    			

Possible Problems


Keywords: IMAP3, POSTFIX, SMTP, AUTH, SASL

Categories: SuSE Linux IMAP Server

Feedback welcome: Send Mail to srsimai@suse.de (Please give the following subject: SDB-rsimai_imap_smtp_auth)
SDB-rsimai_imap_smtp_auth, Copyright SuSE Linux AG, Nürnberg, Germany - Version: 24. Apr 2002
SuSE Linux AG - Last generated: 22. Mai 2002 by ip (sdb_gen 1.40.0)