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===== Message-IDs and spool files =====

The message-IDs that Exim uses to refer to messages in its queue are
mixed-case alpha-numeric, and take the form of: XXXXXX-YYYYYY-ZZ. Most
commands related to managing the queue and logging use these
message-ids.

There are three -- count 'em, THREE -- files for each message in the
spool directory. If you're dealing with these files by hand, instead of
using the appropriate exim commands as detailed below, make sure you get
them all, and don't leave Exim with remnants of messages in the queue. I
used to mess directly with these files when I first started running Exim
machines, but thanks to the utilities described below, I haven't needed to
do that in many months.

Files in /var/spool/exim/msglog contain logging information for each message
and are named the same as the message-id.

Files in /var/spool/exim/input are named after the message-id, plus a suffix
denoting whether it is the envelope header (-H) or message data (-D).

These directories may contain further hashed subdirectories to deal with
larger mail queues, so don't expect everything to always appear directly in the
top /var/spool/exim/input or /var/spool/exim/msglog directories; any searches
or greps will need to be recursive. See if there is a proper way to do what
you're doing before working directly on the spool files.


===== Basic information =====

==== Print a count of the messages in the queue: ====

<code>
**root@localhost#** exim -bpc
</code>

==== Print a listing of the messages in the queue (time queued, size, message-id, sender, recipient): ====

<code>
**root@localhost#** exim -bp
</code>

==== Print a summary of messages in the queue (count, volume, oldest, newest, domain, and totals): ====

<code>
**root@localhost#** exim -bp | exiqsumm
</code>


==== Print what Exim is doing right now: ====

<code>
**root@localhost#** exiwhat
</code>

==== Test how exim will route a given address: ====

<code>
**root@localhost#** exim -bt alias@localdomain.com
user@thishost.com <-- alias@localdomain.com
  router = localuser, transport = local_delivery
**root@localhost#** exim -bt user@thishost.com
user@thishost.com
  router = localuser, transport = local_delivery
**root@localhost#** exim -bt user@remotehost.com
  router = lookuphost, transport = remote_smtp
  host mail.remotehost.com [1.2.3.4] MX=0
</code>

==== Run a pretend SMTP transaction from the command line, as if it were coming from the given IP address.====
This will display Exim's checks, ACLs,
and filters as they are applied. The message will NOT actually be
delivered.

<code>
**root@localhost#** exim -bh 192.168.11.22
</code>

==== Display all of Exim's configuration settings: ====

<code>
**root@localhost#** exim -bP
</code>



=====Searching the queue with exiqgrep=====

Exim includes a utility that is quite nice for grepping through the
queue, called exiqgrep.
[[http://www.exim.org/exim-html-4.50/doc/html/spec_49.html#IX2895 | Learn it. Know it. Live it.]] 
If you're not using this, and if you're not
familiar with the various flags it uses, you're probably doing things the
hard way, like piping `exim -bp` into awk, grep, cut, or `wc -l`. Don't
make life harder than it already is.

First, various flags that control what messages are matched. These can
be combined to come up with a very particular search.

==== Use -f to search the queue for messages from a specific sender: ====

<code>
**root@localhost#** exiqgrep -f [luser]@domain
</code>

==== Use -r to search the queue for messages for a specific recipient/domain: ====

<code>
**root@localhost#** exiqgrep -r [luser]@domain
</code>

==== Use -o to print messages older than the specified number of seconds. ====
For example, messages older than 1 day:

<code>
**root@localhost#** exiqgrep -o 86400 [...]
</code>

==== Use -y to print messages that are younger than the specified number of seconds. ====
 For example, messages less than an hour old:

<code>
**root@localhost#** exiqgrep -y 3600 [...]
</code>

==== Use -s to match the size of a message with a regex. ====
For example, 700-799 bytes:

<code>
**root@localhost#** exiqgrep -s '^7..$' [...]
</code>

==== Use -z to match only frozen messages, or -x to match only unfrozen messages. ====

===== There are also a few flags that control the display of the output. =====

==== Use -i to print just the message-id as a result of one of the above two searches: ====

<code>
**root@localhost#** exiqgrep -i [ -r | -f ] ...
</code>

==== Use -c to print a count of messages matching one of the above searches: ====

<code>
**root@localhost#** exiqgrep -c ...
</code>

==== Print just the message-id of the entire queue: ====

<code>
**root@localhost#** exiqgrep -i
</code>


=====Managing the queue=====

The main exim binary (/usr/sbin/exim) is used with various flags to make
things happen to messages in the queue. Most of these require one or more
message-IDs to be specified in the command line, which is where `exiqgrep
-i` as described above really comes in handy.

==== Start a queue run: ====

<code>
**root@localhost#** exim -q -v
</code>

==== Start a queue run for just local deliveries: ====

<code>
**root@localhost#** exim -ql -v
</code>

==== Remove a message from the queue: ====

<code>
**root@localhost#** exim -Mrm <message-id> [ <message-id> ... ]
</code>

==== Freeze a message: ====

<code>
**root@localhost#** exim -Mf <message-id> [ <message-id> ... ]
</code>

==== Thaw a message: ====

<code>
**root@localhost#** exim -Mt <message-id> [ <message-id> ... ]
</code>

==== Deliver a message, whether it's frozen or not, whether the retry time has been reached or not: ====

<code>
**root@localhost#** exim -M <message-id> [ <message-id> ... ]
</code>

==== Deliver a message, but only if the retry time has been reached: ====

<code>
**root@localhost#** exim -Mc <message-id> [ <message-id> ... ]
</code>

==== Force a message to fail and bounce as "cancelled by administrator": ====

<code>
**root@localhost#** exim -Mg <message-id> [ <message-id> ... ]
</code>

==== Remove all frozen messages: ====

<code>
**root@localhost#** exiqgrep -z -i | xargs exim -Mrm
</code>

==== Remove all messages older than five days (86400 * 5 = 432000 seconds): ====
<code>
**root@localhost#** exiqgrep -o 432000 -i | xargs exim -Mrm
</code>

==== Freeze all queued mail from a given sender: ====

<code>
**root@localhost#** exiqgrep -i -f luser@example.tld | xargs exim -Mf
</code>

==== View a message's headers: ====

<code>
**root@localhost#** exim -Mvh <message-id>
</code>

==== View a message's body: ====

<code>
**root@localhost#** exim -Mvb <message-id>
</code>

==== View a message's logs: ====

<code>
**root@localhost#** exim -Mvl <message-id>
</code>

==== Add a recipient to a message: ====

<code>
**root@localhost#** exim -Mar <message-id> <address> [ <address> ... ]
</code>

==== Edit the sender of a message: ====

<code>
**root@localhost#** exim -Mes <message-id> <address>
</code>



===== Access control =====

Exim allows you to apply
[[http://www.exim.org/exim-html-4.50/doc/html/spec_39.html | access control lists]]
at various points of the SMTP transaction by specifying an ACL to use and
defining its conditions in exim.conf. You could start with the HELO
string.

<code>#
Specify the ACL to use after HELO
acl_smtp_helo = check_helo

# Conditions for the check_helo ACL:
check_helo:

    deny message = Gave HELO/EHLO as "friend"
    log_message = HELO/EHLO friend
                condition = ${if eq {$sender_helo_name}{friend} {yes}{no}}

    deny message = Gave HELO/EHLO as our IP address
    log_message = HELO/EHLO our IP address
    condition = ${if eq {$sender_helo_name}{$interface_address} {yes}{no}}

    accept
</code>

NOTE: Pursue HELO checking at your own peril.  The HELO is fairly
unimportant in the grand scheme of SMTP these days, so don't put too much
faith in whatever it contains.  Some spam might seem to use a telltale HELO
string, but you might be surprised at how many legitimate messages start
off with a questionable HELO as well.  Anyway, it's just as easy for a
spammer to send a proper HELO than it is to send HELO im.a.spammer, so
consider yourself lucky if you're able to stop much spam this way.

Next, you can perform a check on the sender address or remote host.
This shows how to do that after the RCPT TO command; if you reject here, as
opposed to rejecting after the MAIL FROM, you'll have better data to
log, such as who the message was intended for.

<code>
# Specify the ACL to use after RCPT TO
acl_smtp_rcpt = check_recipient

# Conditions for the check_recipient ACL
check_recipient:

    # [...]

    drop hosts = /etc/exim_reject_hosts
    drop senders = /etc/exim_reject_senders

    # [ Probably a whole lot more... ]
</code>

This example uses two plain text files as blacklists. Add appropriate
entries to these files - hostnames/IP addresses to /etc/exim_reject_hosts,
addresses to /etc/exim_reject_senders, one entry per line.

It is also possible to perform
[[http://www.exim.org/exim-html-4.50/doc/html/spec_40.html|content
scanning]] using a regex against the body of a message, though obviously
this can cause Exim to use more CPU than it otherwise would need to,
especially on large messages.

<code>
# Specify the ACL to use after DATA
acl_smtp_data = check_message

# Conditions for the check_messages ACL
check_message:

   
    deny message = "Sorry, Charlie: $regex_match_string"
    regex = ^Subject:: .*Lower your self-esteem by becoming a sysadmin

    accept
</code>


===== Fix SMTP-Auth for Pine =====

If pine can't use SMTP authentication on an Exim host and just returns
an "unable to authenticate" message without even asking for a password, add
the following line to exim.conf:

<code>
begin authenticators

  fixed_plain:
  driver = plaintext
  public_name = PLAIN
  server_condition = "${perl{checkuserpass}{$1}{$2}{$3}}"
  server_set_id = $2
>**  server_prompts = :**
</code>

This was a problem on CPanel Exim builds awhile ago, but they seem to
have added this line to their current stock configuration.


====Log the subject line====

This is one of the most useful configuration tweaks I've ever found for
Exim. Add this to exim.conf, and you can log the subject lines of messages
that pass through your server. This is great for troubleshooting, and for
getting a very rough idea of what messages may be spam.

<code>
log_selector = +subject
</code>

[[http://www.exim.org/exim-html-4.50/doc/html/spec_48.html#SECT48.15 | Reducing or increasing what is logged]].


====Disable identd lookups====

Frankly, I don't think [[http://www.ietf.org/rfc/rfc1413.txt | identd ]] has been useful for a
long time, if ever.  Identd relies on the connecting host to confirm the
identity (system UID) of the remote user who owns the process that is
making the network connection.  This may be of some use in the world of
shell accounts and IRC users, but it really has no place on a high-volume
SMTP server, where the UID is often simply "mail" or whatever the remote
MTA runs as, which is useless to know. It's overhead, and results in
nothing but delays while the identd query is refused or times out. You
can stop your Exim server from making these queries by setting the timeout
to zero seconds in exim.conf:

<code>
rfc1413_query_timeout = 0s
</code>


====Disable Attachment Blocking====

To disable the executable-attachment blocking that many Cpanel servers
do by default but don't provide any controls for on a per-domain basis, add
the following block to the beginning of the /etc/antivirus.exim file:

<code>
if $header_to: matches "example\.com|example2\.com"
then
  finish
endif
</code>

It is probably possible to use a separate file to list these domains,
but I haven't had to do this enough times to warrant setting such a thing
up.


===== Searching the logs with exigrep =====

The [[ http://www.exim.org/exim-html-4.50/doc/html/spec_49.html#IX2911 | exigrep ]]
utility (not to be confused with exiqgrep) is used to search an exim log
for a string or pattern. It will print all log entries with the same
internal message-id as those that matched the pattern, which is very handy
since any message will take up at least three lines in the log. exigrep
will search the entire content of a log entry, not just particular
fields.

==== One can search for messages sent from a particular IP address: ====

<code>
**root@localhost#** exigrep '<= .* \[12.34.56.78\] ' /path/to/exim_log
</code>

==== Search for messages sent to a particular IP address: ====

<code>
**root@localhost#** exigrep '=> .* \[12.34.56.78\]' /path/to/exim_log
</code>

This example searches for outgoing messages, which have the "=>"
symbol, sent to "user@domain.tld".  The pipe to grep for the "<=" symbol
will match only the lines with information on the sender - the From
address, the sender's IP address, the message size, the message ID, and the
subject line if you have enabled logging the subject. The purpose of doing
such a search is that the desired information is not on the same log line
as the string being searched for.

<code>
**root@localhost#** exigrep '=> .*user@domain.tld' /path/to/exim_log | fgrep '<='
</code>

==== Generate and display Exim stats from a logfile: ====

<code>
**root@localhost#** eximstats /path/to/exim_mainlog
</code>

=== Same as above, with less verbose output:====

<code>
**root@localhost#** eximstats -ne -nr -nt /path/to/exim_mainlog
</code>

==== Same as above, for one particular day: ====

<code>
**root@localhost#** fgrep YYYY-MM-DD /path/to/exim_mainlog | eximstats
</code>

===== Bonus! =====

=== To delete all queued messages containing a certain string in the body: ====

<code>
**root@localhost#** grep -lr 'a certain string' /var/spool/exim/input/ | sed -e 's/^.*\/\([a-zA-Z0-9-]*\)-[DH]$/\1/g' | xargs exim -Mrm
</code>

Note that the above only delves into /var/spool/exim in order to grep
for queue files with the given string, and that's just because exiqgrep
doesn't have a feature to grep the actual bodies of messages. If you are
deleting these files directly, YOU ARE DOING IT WRONG! Use the appropriate
exim command to properly deal with the queue.

If you have to feed many, many message-ids (such as the output of an
`exiqgrep -i` command that returns a lot of matches) to an exim command,
you may exhaust the limit of your shell's command line arguments.  In that
case, pipe the listing of message-ids into xargs to run only a limited
number of them at once. For example, to remove thousands of messages sent
from joe@example.com:

<code>
**root@localhost#** exiqgrep -i -f '<joe@example.com>' | xargs exim -Mrm
</code>


===== Reload the configuration =====

After making changes to exim.conf, you need to give the main exim pid a
SIGHUP to re-exec it and have the configuration re-read. Sure, you could
stop and start the service, but that's overkill and causes a few seconds of
unnecessary downtime. Just do this:

<code>
root@localhost# kill -HUP `cat /var/spool/exim/exim-daemon.pid`
</code>

You should then see something resembling the following in exim_mainlog:

<code>
pid 1079: SIGHUP received: re-exec daemon
exim 4.52 daemon started: pid=1079, -q1h, listening for SMTP on port 25 (IPv4)
</code>
  

====Read The Fucking Manual====

[[ http://www.exim.org/ | The Exim Home Page ]]

[[ http://www.exim.org/docs.html | Documentation For Exim ]]

[[ http://www.exim.org/exim-html-4.50/doc/html/spec.html | The Exim Specification - Version 4.5x ]]

[[ http://www.exim.org/exim-html-4.50/doc/html/spec_5.html#IX199 | Exim command line arguments ]]