In the last year I had some discussions with DIYMacServer users on how to upgrade their machine or even move their setup to some new hardware. The biggest issue or problem they encountered was how to safely move the emails stored on the server. In this post I will try to describe one way (there are more possibilities to do this) that is pretty safe and you won’t lose any mail.
Before you start please check if you have enough diskspace to make an archive of the mail directory, it might have become very big. You can check the size of the directory by using the command:
sudo du -hc /usr/local/virtual
The last line from the output will tell you how much space you need on your disk. If you haven’t got enough room you can ask your users to empty their Trash and Sent mail in their email application or remove some items you have stored on the server yourself. If that ain’t possible you’ll need to buy an extra drive (external or internal, depending on the machine you’ve got).
If you have users other then yourself using the mail-server please inform them in advance that the mail-server is going off-line for a short period at a time that is convenient for you to perform this task. This is only about moving the mail, not the websites and I’m assuming you’ve got the other machine ready and setup to take over.
When the time has comes, take the IMAP server off-line, to prevent users from accessing their IMAP folders and accidentally do something between backup and restore actions. If you’ve got POP3 configured as well please stop that as well.
Stop Postfix to prevent incoming mail to be lost when it arrives between backup and restore actions.
Now everything is stopped and you are ready to make a backup of the email directory.
You can do this by using the following command:
sudo tar -czf mailbackup.tar.gz /usr/local/virtual
This will create a big file called ‘mailbackup.tar.gz’, you can copy/move/ftp this file to any destination you would like.
To unpack the backup and restore it to it’s new destination please use the following command:
sudo tar -xzf /locationofarchive/mailbackup.tar.gz
Replace ‘locationofarchive’ with the path to where you stored your backup archive.
If you used the same setup on both machines the mail directory should have the proper security settings and ownership. You can test this by using the following command:
sudo ls -l /usr/local/virtual
The owner of the directories should be postfix or vmail, depending on your setup.
Now you can start the IMAP server first and check with your own mail client if you can access all your email again on the server. If there is a problem please check your logfile (/var/log/mail.log for a possible explanation). If it all works turn on the Postfix server and send yourself an email using another mailserver (use a webbased service like Gmail, Yahoo mail or Hotmail) and check if the email will arrive in your mailbox. Keep an eye on the logfile to see the email coming in.
If everything is working for you inform your users that it is all right to use the mail-server and if they have any issues that they please inform you about it.