compression for large Maildir structure

Question

I run a Debian Linux mailserver for a few little companies that stores its emails in a Maildir structure and therefore each mail as a seperate plain text file.

Altogether these files are as large as about 45 GB.

Even though I am backing up the files online I want to download them to store them on another physical backup media.

Evaluated statistically each 5th mail has one file attachment being as large as about 1.2MB. What would be a good compression for this files? The speed of the compression is of low priority because I do only work on archived data not the productive one.

I am not asking for the "best" solution as I know there isn't one but am looking for your recommendations.

Answer 1

Use tar to create an archive, then compress the archive with something simple, like plain gzip, or something that compresses better, like xz --best -e. Then transfer the compressed archive to the backup media.