• Lets you delegate administration of a portion of a virtual domain map to the user(s) responsible for the domain.
• User-friendly interface resembling an Excel spreadsheet
• Meant to run as a standalone service owned by the Postfix user (or at least a user or group with write access to the Postfix config files), and thus does not require granting your web server any particular privileges.
• Fully self-contained executable, no dependencies
• Will allow users to create aliases for valid RFC-5322 email addresses or use existing local addresses, but not dangerous functionality like command delivery
• manages a spam map file in access(5) format when the recipient starts with 550
• optionally run a script after the map files are updated, e.g. to sort the files, commit changes in git, etc.

• Go 1.16 or later
• Git

• Run "make".

Postmapweb is configured using a JSON file, by default /etc/postfix/postmapweb.json. It can handle multiple domains, but only one map file per domain.

To create the config file (if it does not already exist), add a domain to it and set up a password for it (or change the password):

postmapweb -c <config file> -d <domain> -m <Postfix map file>

To start the server:

postmapweb -c <config file> -p :<port>

Warning: postmapweb must be run behind a HTTPS reverse proxy server, e.g. nginx or HAProxy. Do not run it without encryption or expose it to the Internet by binding it elsewhere than localhost!

The config files in /etc/postfix are owned by root, not postfix, and it is not good practice to run a server such as this as root. Fortunately the virtual_alias_maps Postfix configuration directive accepts multiple maps. My recommended configuration is to create a new user postmapweb in the postfix group, create a subdirectory /etc/postfix/domains owned by postmapweb and create one virtual map file per domain there. Make sure you remove any entries from /etc/postfix/virtual when you migrate them to /etc/postfix/domains/<example.com> as Postfix looks up aliases in the order of the files, and thus any change to an alias in /etc/postfix/domains/<example.com> would be preempted by the leftover entry in /etc/postfix/virtual.

Thus:

(backup your /etc/postfix directory)
useradd -d /etc/postfix/domains -s /bin/sh -G postfix postmapweb
(or whatever the equivalent is on your operating system)
mkdir /etc/postfix/domains
grep example.com /etc/postfix/virtual > /etc/postfix/domains/example.com
postmap /etc/postfix/domains/example.com
chown -R postmapweb:postfix /etc/postfix/domains
(assuming your existing virtual_alias_maps = dbm:/etc/postfix/virtual, adjust to taste)
postconf -e virtual_alias_maps=dbm:/etc/postfix/virtual,dbm:/etc/postfix/domains/example.com
postfix reload
grep -v example.com /etc/postfix/virtual > /tmp/foo;cat /tmp/foo > /etc/postfix/virtual
postmap /etc/postfix/virtual
postfix reload
postmapweb -c /etc/postfix/postmapweb.json -d example.com -m /etc/postfix/domains/example.com
postmapweb -v -c /etc/postfix/postmapweb.json

You can set the script key in the JSON config file (manual edit of the file is required). It will be run in the same working directory as postmapweb, and the domain name of the changes will be passed as argument 1.

Here is the script I use to sort my files. I have one $domain and one $domain.spam file per domain under /etc/postfix/domains:

#!/bin/sh
cd /etc/postfix/domains
for x in *.dir; do
    f=`echo $x|sed -e 's/.dir$//g'`
    echo sorting $f
    case $f in
	*.spam)
	    gsort $f > $f.tmp
	    ;;
	*)
	    head -1 $f > $f.tmp
	    tail +2 $f | gsort >> $f.tmp
	    ;;
    esac
    mv $f.tmp $f
    postmap $f
    chown postmapweb:postfix $f*
done
postfix reload

  -c string
        config file to use (default "/etc/postfix/postmapweb.json")
  -cpuprofile string
        write cpu profile to file
  -d string
        add domain user
  -m string
        virtual domain map to use with -d (default "/etc/postfix/virtual")
  -p string
        host address and port to bind to (default "localhost:8080")
  -v    verbose logging
  -w string
        password to use with -d (insecure!)

• Go: https://golang.org/
• HandsOnTable: http://handsontable.com/
• And of course Wietse Venema's Postfix: http://www.postfix.org/