The last four maybe five years, I have been running my own personal email server. Mainly because I was having privacy issues with all the main providers but also as my particular interest of keeping my digital life.. well, just mine.
Anyway, the interesting part here is that I was looking for a way to push my backups from the email server to my NAS at home which is running the SSH on a non-standard port.
The secret here is the switch “-e” that allows you to pass a custom string to rsync.
rsync -a -e "ssh -p 2222" /path/of/your/folder/ email@example.com:/path/to/backup