Add a domain to postfix configuration – temporary solution src

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postfix -e mydestination="example.org, example.com, example.net"

Now local users receive mails from all domans, i.e. user malpka will receive mails from malpka@example.org, malpka@example.com and malpka@example.net. Mails are saved in /var/mail/malpka

Separate mail from UNIX-accounts

Add vmail directory and vmail user

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mkdir -p /var/vmail
groupadd -g 5000 vmail
useradd -g vmail -u 5000 vmail -d /var/vmail -m
chown -R vmail:vmail /var/vmail
chmod u+w /var/vmail

Reconfigure postfix to use virtual

Let’s add a mail subdomain

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example.org   IN MX  1   example.com

Postfix reconfiguration

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postconf -e virtual_mailbox_domains=example.org
postconf -e virtual_mailbox_base=/var/vmail
postconf -e virtual_mailbox_maps=hash:/etc/postfix/virtual_mailbox_maps
postconf -e virtual_minimum_uid=100
postconf -e virtual_uid_maps=static:5000
postconf -e virtual_gid_maps=static:5000
postconf -e virtual_alias_maps=hash:/etc/postfix/virtual_alias_maps

• virtual_mailbox_domains – comma separated list of domains that are handled by postfix’ virtual domains mechanism. The rest (from mydestination) is handled as a local mail.
• virtual_mailbox_base – base folder for virtual mailboxes. This is the prefix that is prepended to the items from virtual_mailbox_maps
• virtual_mailbox_maps – location of mailboxes for accounts
• virtual_minimum_uid – safety reasons
• virtual_uid_maps, virtual_gid_maps – user/group for writing

Domain listed in virtual_mailbox_domains must not be present in mydestination

Mailbox maps

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echo "malpka@example.org example.org/malpka" >> virtual_mailbox_maps
echo "@example.org example.org/catchall" >> virtual_mailbox_maps

If you would like to use Maildir format instead of MBox, just add slash (example.org/malpka/)

Aliases

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echo "malpka2@example.org malpka" >> virtual_alias_maps

Hash configuration files

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postmap virtual_alias_maps
postmap virtual_mailbox_maps

Create mailbox file and setup permission again.

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touch /var/vmail/example.org/malpka
touch /var/vmail/example.org/catchall

chown -R vmail:vmail /var/vmail
chmod u+w /var/vmail

Reload postfix configuration

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postfix reload

Test

Receive mail.

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mutt -f /var/vmail/example.org/malpka

Remarks

• Despite every email address has it’s own place (different MBox/Maildir) you can only access it from the local system (root or vmail user). Fix in Part 4 – dovecot.
• the mails that you send from a local accounts will still be from $myorigin domain
• MBox vs Maildir war
• postfix virtual_* configuration can be moved to a database, when needed (more users)