Why does email get delivered internally when Internet's down

[hillboy]

I apologize if this is a really stupid question, but....why is that when we can still get internal email when we do not have access to the Internet?

We are only using SMTP protocol for email (and x400). I thought that all email had to go to our ISP's DNS server for resolution (even though the location of the mailbox is located on the internal mail server)because of our use of SMTP.

Any explanation would be greatly appreciated...

 

[brontosaurus]

internal mail uses X.400 and has no need to touch the IMS anyway. When you send an email, exchange server first checks it's "local" directory to see if it can be delivered without further intervention....

 

[hillboy]

Thanks brontosaurus...I thought that that may be the case but could find no info. indicating such.

 

[Chutta]

Even if you were using a pure SMTP enviornment, and you didn't muck with any registry settings, Exchange cache's its DNS lookups for I THINK (could be wrong) for 24 hours.