Thank you for the link.
Indeed the Attach Contact zimlet can indeed be useful, the suggestion is appreciated.
However it should be noted that
The Attach Contact Zimlet doesn't backup all fields, unlike CSV file backup (it use Zimbra's vCards).
Zimbra's vCards currently destroy a lot of data - such as: multiple URL fields; multiple addresses; ALL Company phone numbers; multiple IM addresses; multiple mobile numbers; and ALL custom field data!
See my attachment at:
https://bugzilla.zimbra.com/show_bug.cgi?id=59352
Also, it's not really practical if you're dealing with thousands.
Fixing the bugs I've linked to is essential and I hope will be targetted for Helix - enterprise users who use contact export to backup (as recommended in Zimbra documentation) expect their data to be backed-up, they don't expect to later realise a lot of data is missing).
Fixing those bugs would be trivial. (Especially simply adding a Category field in contact export).