Linux Mail Server Setup and Howto Guide » Backup

Backup Postfix Mailbox

consultant — Sun, 09 May 2010 12:36:48 +0000

Backing up your mailboxes is a simple as copying your mailbox folder. This article describes how to backup and restore your Postfix mailboxes using the tar command.

To backup the mailbox, type the command below in a terminal window.

tar cvzf mailbox-`date +%F_%H%M`.tar.gz /home/vmail

Replace /home/vmail with the location of your own mailbox.

To restore the mailbox, type the command below in a terminal window.

tar xvzf mailbox.tar.gz -C /

Replace mailbox.tar.gz with the name of your backup file.

Ideally, the Postfix and Dovecot configurations should be documented, or better yet, maintained using a change configuration process. But you can also use the procedure above to backup the /etc directory although it is not recommended since you may restore your configuration on an updated OS.

Backup Incoming Mail in Postfix

consultant — Sun, 13 Dec 2009 03:59:27 +0000

This article will show you how to copy incoming mail to another mail server using the blind carbon copy (BCC) feature in Postfix. This capability is useful for backup, archive or disaster recovery purposes.

1. Edit the file /etc/postfix/main.cf and add the lines below.

recipient_bcc_maps = pcre:/etc/postfix/backup_bcc.pcre
transport_maps = hash:/etc/postfix/transport
smtp_generic_maps = pcre:/etc/postfix/generic.pcre

2. Create the file /etc/postfix/backup_bcc.pcre containing

/^(.*)@acme\.local$/ $1@backup.invalid

which tells Postfix to BCC emails to the domain backup.invalid.

Email for	BCC to
johndoe@acme.local	johndoe@backup.invalid
janedoe@acme.local	janedoe@backup.invalid

3. Edit the file /etc/postfix/transport and add the line below.

backup.invalid smtp:[192.168.1.4]

Replace the IP address with the IP address of your backup mail server.

Next, type in the command below to convert it to a database file.

postmap /etc/postfix/transport

This tells Postfix to send all emails for the domain backup.invalid to the specified mail server.

4. Create the file /etc/postfix/generic.pcre containing

/^(.*)@backup\.invalid$/ $1@acme.local

which tells Postfix to change the email address back to the original recipient before sending it out.

BCC to	Email for
johndoe@backup.invalid	johndoe@acme.local
janedoe@backup.invalid	janedoe@acme.local

5. Restart the Postfix or MailScanner service if you have installed it. Learn how to start and stop services here.

The destination Postfix server can be configured to accept emails without validating the recipient.

If you encounter any problems, check the log file at /var/log/maillog.

Postfix Backup MX

consultant — Sat, 14 Nov 2009 15:42:49 +0000

Postfix can be configured to act as a backup mail server. A backup MX server accepts mail if the primary mail server goes down and will forward all mails in its queue if the primary mail server goes back online.

This article describes how to configure Postfix to act as a backup MX server.

Configuring Postfix

1. Edit the file /etc/postfix/main.cf and update the lines below.

mynetworks = 127.0.0.0/8
relay_domains = example.com
smtpd_recipient_restrictions = permit_mynetworks, 
    reject_unauth_destination
transport_maps = hash:/etc/postfix/transport

2. Edit the file /etc/postfix/transport and add the line below.

example.com :[192.168.1.3]

Replace 192.168.1.3 with the hostname or IP address of your primary mail server.

3. Type the line command below to create a transport database file.

postmap /etc/postfix/transport

4. Restart the Postfix or MailScanner service if you have installed it. Learn how to start and stop services here.

5. You should now be able to send mails to your backup mail server and those mails will be automatically forwarded to your primary mail server. See Test Postfix using Telnet.

Backup MX Notes

It is easy to setup a backup mail server but you also need to consider the items below.

Add DNS MX Record. In order for your backup mail server to be identified over the internet, you need to add a lower priority DNS MX record. A higher number means lower priority.

Domain TTL Priority Mail Server Name

acme.local 86400 10 mail.acme.local

acme.local 86400 20 mail2.acme.local
Add Antivirus and Antispam Filtering. Make sure to have the same or better virus and spam protection in your backup mail server as you have in your primary mail server. Otherwise, viruses and spams will be entering your inbox through the backdoor.
Verify Recipient. If possible, you also need to apply the same recipient verification method you used in your primary mail server. This will allow your backup mail server to reject all invalid recipient address instead of having the primary mail server bounce the forwarded emails with invalid recipients. Use the relay_recipient_maps setting in /etc/postfix/main.cf to specify the valid recipients.
Relay Only. In your /etc/postfix/main.cf, make sure the relay domain is not found in mydestination, virtual_alias_domains and virtual_mailbox_domains. Otherwise, the backup mail server will not forward emails to the primary mail server and will instead store it into its own mailbox.
Use IP Address. By specifying the hostname or IP address in the transport file, the DNS MX lookup can be eliminated. Specifying the IP address will be even better since this will eliminate the need for any DNS lookup. It will also avoid relay loopback problems if you are using port forwarding in your backup mail server.
Flush Mail Queue. You can force Postfix to immediately send all the mail in its queue by typing in the command below. This useful after bringing the primary mail server back online to eliminate the waiting period for the backup mail server to resend mails in its queue.
```
postfix flush
```

Domain	TTL	Priority	Mail Server Name
acme.local	86400	10	mail.acme.local
acme.local	86400	20	mail2.acme.local