ZhoubaWiki:PostfixTips

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This page contain some usefull commands and tips for using Postfix.

Certificate problems

If postfix can't validate email certificiates mail log will be full of message like these

certificate verification failed for gmail-smtp-in.l.google.com[74.125.196.26]:25: untrusted issuer /C=US/O=Equifax/OU=Equifax Secure Certificate Authority

Check if certificates are installed and updated in /etc/ssl/certs/, if they are set path to them manually by adding line to /etc/postfix/main.cf.

smtp_tls_CAfile = /etc/ssl/certs/ca-certificates.crt

Checking mail queue

To check current mail queue use: postqueue -p | tail -n 1 | cut -d' ' -f5

Searching and restoring emails in SPAM folder

Default spam folder is /var/lib/amavis/virusmails.

To find name of spam email containing KEYWORD:

cd /var/lib/amavis/virusmails
find . -name "*spam*.gz" -exec zgrep -l 'KEYWORD' {} \;| cut -c 3-

To copy spam to original recipient mailbox, EMAILNAME should be relative to spam folder.

amavisd-release EMAILNAME

To release found mail:

find . -name "*spam*.gz" -exec zgrep -l 'KEYWORD' {} \;| cut -c 3- | xargs -L 1 amavisd-release

How to move Postfix mail queue

This document describes how to move Postfix mail queue from one server to another without downtime.

  • ServerA - server with queue we want to move
  • ServerB - server with install working Postfix

Before start, check both ServerA and ServerB hold queue /var/spool/postfix/hold. Any email in hold queue will be send. In case there are emails in hold that should not be send move them out of hold folder.

ServerA

Move all waiting emails to hold queue.

postsuper -h ALL

Tar hold folder and copy it to ServerB.

tar -zcvf postfixhold.tar.gz /var/spool/postfix/hold
scp postfixhold.tar.gz user@ServerB:/home/user/

ServerB

Untar to /var/spool/postfix/hold.

tar -C / -zxvf postfixhold.tar.gz

Number of added hold emails should increase queued emails (Protip: run this command before untaring hold emails)

postqueue -p | tail -n 1 | cut -d' ' -f5

Put emails from hold to deferred queue.

postsuper -H ALL

Manual recommends releasing emails near maximal wait time directly to active queue.

postsuper -r ALL hold

ServerA

Now remove whole hold queue on ServerA.

postsuper -d ALL hold


Log statistics

One of tools for generating statistics from email logs is Pflogsumm.

Installation

sudo curl -O http://jimsun.linxnet.com/downloads/pflogsumm-1.1.3.tar.gz
sudo tar -xzf pflogsumm-1.1.3.tar.gz

Usage

./pflogsumm.pl /var/log/email.log > report.txt

Getting message id

Getting message id from mail where argo or bugweis is mentioned

mailq | grep -v '^ *(' | awk 'BEGIN { RS = "" } { if ($0 ~ /(argo22\.)|(bugweis\.)/) print $1 }' | tr -d '*!'

Release multiple emails from hold

Can be connected wtih 'Getting message id' command and output piped directly to postsuer. -H - will read message ID from input.

cat ouremails_ID.txt | postsuper -H -

Removing emails for whole domain

First be sure you know what are you doing, this will DELETE most of emails in standard email directory! Running script at wrong place can cripple the company!

Backup vhole email directory (/var/vmail/DOMAIN/).

Run following script, make sure initial change directory is set correctly

cd /var/vmail/DOMAIN;
for DIR in `ls -l`; do rm -vf $DIR/Maildir/cur/*;rm -vf $DIR/Maildir/new/*;rm -vf $DIR/Maildir/.*/cur/*;rm -vf $DIR/Maildir/.*/new/*; done;