[K12OSN] Moving our email server

[Les Mikesell]

On Fri, 2007-01-05 at 11:59 -0500, mrok12osn at eastgranby.k12.ct.us wrote:

> You read the question correctly.  I will take a hard look at the config
> files that you mentioned.  Regarding DNS TTL, I may have trouble
> coordinating the changes because I cannot directly update our DNS
> pointers.  I need to have Cox personnel do it.

If you can have it changed twice, add the new address as a 2nd
equal-weight MX ahead of time.  Senders will always try both if
one fails so for the transition you can answer on either.  After
the cutover, have the old one removed.  MX records only apply
to smtp senders though.  If you have people connecting to pick
up email with POP or IMAP on the public address they will have
to wait until the A record changes in DNS.

> If I do not need to make any changes to the config files, can you expound
> at all about "a little stupid" regarding the connections to two ISP's?

You can have multiple addresses (even on a single NIC), but you
will only have one default gateway and return packets don't track
the inbound path so you'll often be sending back the wrong way.
Normally this will work anyway, but you can have some problems.

-- 
  Les Mikesell
   les at futuresource.com