Virtualmin should not delete off-server MX records

I had a domain with DNS and Mail enabled, but with MX records set to point to Postini for offsite spam filtering.

Mail service for this domain was then moved to another server, so I unchecked the "Mail for domain enabled?" box, at which point all MX records were wiped from DNS.

I believe it makes sense to remove any MX records pointing at the local server, but it should not touch off-server MX records since they may still remain relevant.