Hi,

I am using restic to backup my email (stored in dovecot Maildir format) to Amazon S3

As each message is a separate file on disk, and those files don't change after the email has been delivered and read by the user, the incremental backup each day is fairly efficient as it only stored new mails.

However, the dovecot-uidlist files change frequently, and are often quite large. The restic backup program detects the file has changed and uploads a new version, but is not smart enough to detect that only a few lines have changed, so it uploads a fresh copy of the entire file to remote storage.

I have done some test backups and have noticed, that if I exclude those files from the backup, it completes much faster and uploads far less. Would this be a reasonable policy?

My backup is mainly there against unlikely but severe events such as complete hard drive failure, so if I ever had to use it, I would not mind wating for my email client to re-download all my emails.

-- David Pottage