1. Debian Exim4 User FAQ

This is work in progress, so it is probably not yet very helpful.

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1.1. Questions not categorized yet

1.1.1. How do I re-execute the debconf-driven configuration?

1.1.2. When I try to deliver a message via SMTP to my Exim, I get "550 relay not permitted"

Answer not yet fleshed out.

1.1.3. I cannot connect to my Exim from my home connection. From internet hosts, it works

Answer not yet fleshed out.

One possible answer to why your local (home) connection is not sending out email is that your ISP blocks port 25 further upstream from you. This prevents computers on your ISP's network (including yours) from sending out mail. Many ISPs do this as a security precaution because "Zombie" computers can be used to send out spam.

One possible solution is to use another port to send your mail. You will have to configure your runtime configuration file which under debian and ubuntu is /etc/exim4/exim4.conf.template. Edit that file and place under main/02_exim4-config_options this line;

daemon_smtp_ports=smtp : 587

This allows the exim4 daemon to listen on port 587 and should allow you to send and receive emails on that port.

1.1.4. I am trying to have exim forward mail to some internal hosts, but all I am getting is "all relevant MX records point to non-existent hosts"

A probeble cause for this might be that all MX records for the offending domain point to site local or link local IP addresses, which are ignored by the dnslookup router to protect from misconfigured external domains. The default configuration has relaxed checking for domains that the local system is configured to allow relaying to, so adding the offending domain to dc_relay_domains will most probably help.

Please note that no domain on the public Internet should have MX records pointing to site local or link local IP addresses, so you might check your externally visible MX records.

If this doesn't help, try analyzing the output of exim -d -bt some.local.part@the.offending.domain.example

[http://www.exim.org/eximwiki/FAQ/Routing_to_remote_hosts/Q0302 Upstream Exim FAQ Q0302] might help as well.

1.1.5. What do "lowest numbered MX record points to local host" or "remote host address is the local host" mean?

This is covered in [http://www.exim.org/eximwiki/FAQ/Routing_to_remote_hosts/Q0301 Upstream Exim FAQ Q0301.] The Debian default configuration has the hubbed_hosts router mentioned there already defined. Its configuration file is /etc/exim4/hubbed_hosts, and some documentation can be found in /etc/exim4/conf.d/router/150_exim4-config_hubbed_hosts.

1.1.6. What do the "DEBCONFfooDEBCONF" macros in the Debian configuration do?

When the Exim daemon is started, the dpkg-conffiles in /etc/exim4 are post-processed to the result /var/lib/exim4/config.autogenerated, which is the configuration file that Exim reads. In this post-processing step, done by update-exim4.conf, the DEBCONFfooDEBCONF strings are replaced with values pulled from /etc/exim4/update-exim4.conf.conf and system configuration.

Please note that the string DEBCONF is kind of a misnomer since the strings are _not_ directly pulled from the Debconf database, but from user-editable conffiles instead. This is a common misunderstanding.

For more information, read the update-exim4.conf man page.

1.1.7. I am experiencing timeout issues with TLS connections

Answer not yet fleshed out.

1.1.8. Why does my exim HELO as localhost.localdomain

Answer not yet fleshed out.

1.1.9. How do I configure a catch-all?

Answer not yet fleshed out.

1.1.10. Exim stops delivery after ten messages are received

Answer not yet fleshed out.

1.1.11. How can I debug SMTP AUTH and/or other SMTP aspects

1.1.12. I have configured exim with help of a non-Debian HOWTO. It doesn't work.

Unfortunately, a lot of third-party documentation has been written by people who do not fully understand how things work. They might have been successful in solving the issue at their hands, but challenges are so different that it is extremely improbable that the solution will hold in other situations.

It is thus adviseable to take third-party HOWTOs with extreme caution and use them only as input for a local solution. Taking a third-party configuration snippet verbatim is like asking for extreme trouble.

In this FAQ entry, we'll link to third-party HOWTO documents and comment about what we think about their contents.