Today I calculated the space saved in one of the stores thanks to archiving+compression in one of the Zimbra servers that I’ve installed more than one ayer ago. The archiving volume has 273GB of email that uses 159GB of disk after compression. That’s 42% of saving.
I’m using a script to archive mails in the Open Source Edition that I’ve developed last year, running without any problems for more that 12 months.
It’s in my toolbox: https://github.com/diegows/toolbox