Mail Sync between 2 mailservers using Imapsync

Imapsync is an IMAP transfer tool used for copying emails from one IMAP server to another IMAP server. This article will help you to install imapsync on Ubuntu, Debian, and LinuxMint systems and transfer all your Mailboxes and emails between two IMAP servers.

Step 1 – Install Imapsync
Imapsync package is available under EPEL package repository. First make sure you have added EPEL on your system or install it first.

$ sudo yum install epel-release

Now, install imapsync package using following command.

$ sudo yum install imapsync

At this stage, your system is ready for migration all data from one email account to other email accounts using IMAP.

Step 2 – Transfer Emails with IMAP
So you are ready for migration. Before migration make sure both accounts have IMAP running and accessible from your system. After that use following command syntax.

$ imapsync --host1 imap.source.example.com \
 --user1 user@example.com \
 --password1 S0urcePassw0rd \
 --ssl1 \
 --host2 imap.dest.example.com \
 --user2 user@example.com \
 --password2 Dest1nat10NPassw0rd \
 --ssl2

The command will take a long time as per the size of your source Mailbox. After completing all process, you will see a long list of output. Check the output to find if any error occurred during transfer. Below is the small part of the result.

Transfer started at Thu May 11 11:45:37 2017
PID is 4969
...
...
...
Total bytes transferred : 78373 (76.536 KiB)
Total bytes duplicate host1 : 0 (0.000 KiB)
Total bytes duplicate host2 : 0 (0.000 KiB)
Total bytes skipped : 0 (0.000 KiB)
Total bytes error : 0 (0.000 KiB)
Message rate : 0.1 messages/s
Average bandwidth rate : 3.0 KiB/s
Memory consumption : 217.0 MiB
Biggest message : 57947 bytes (56.589 KiB)
Memory/biggest message ratio : 3927.0
Start difference host2 - host1 : -2 messages, -78373 bytes (-76.536 KiB)
Final difference host2 - host1 : 0 messages, 0 bytes (0.000 KiB)
Detected 0 errors

Src: https://tecadmin.net/use-imapsync-on-ubuntu/