>Given the fact that the DNS entry change may mean that some remote hosts >will continue to direct mail to the old Exchange server for a few days
Easy fix: reduce the TTL on the MX hostnames and their A records to something short, like 5 minutes, until the switch over is done. >The time it will continue to receive email will depend on the TTL >settings stored on the remote hosts who are sending email to the end users. TTL is, or at least should be, implemented only by DNS caches, not in the mail server. >I have seen some misconfigured DNS records that almost never check for >updates on an address because their TTL never flushes their local cache. Then screw their mail deliveries. The self-inflicted punishment might cause them to fix their systems. Len http://MenAndMice.com/DNS-training http://BIND8NT.MEIway.com : ISC BIND for NT4 & W2K http://IMGate.MEIway.com : Build free, hi-perf, anti-abuse mail gateways Please visit http://www.ipswitch.com/support/mailing-lists.html to be removed from this list. An Archive of this list is available at: http://www.mail-archive.com/imail_forum%40list.ipswitch.com/ Please visit the Knowledge Base for answers to frequently asked questions: http://www.ipswitch.com/support/IMail/
