Interactive DNS MX-verify CGI running at 3 different network locations

Enter here the domain, or email address for which you want to have the backup delivery things verified.

Further usage guidance below the alternate entry boxes.

Domain or Email Address: (server at network)

Domain or Email Address: (server at network)

Domain or Email Address: (server at host; With TCP/ECN!)

The domain name (of address!) you give below must have MX records at it. If there are no MXes for given domain, email might get delivered by means of using traditional ``if there are no MXes, use A'' operational rule in the internet. However this utility won't (naturally) have any usefull work in that case, and it reports an error (but continues..)

This does not send any email to you, just does a series of connections, plus interactive reception address tests of following kind:

  RCPT TO:<postmaster@that.domain>
  RCPT TO:<your.address@that.domain>

The explanation:

For each server, it is acceptable to yield:

Anything else means you have to figure out, what is going on. Especially if any backup server rejects the ``RCPT TO'' with 400- or 500-series codes.

All tests this CGI does must yield ``Apparently OK'' if you aspire to have any change at having reliably working incoming email. (or ``Connection Timeout'' or ``Connection Refused'' if your primary server(s) are firewalled, and all traffic must always go via backup servers.)

This CGI utility is one of ZMailer auxiliary utilities, and it was written by Matti Aarnio after he got sufficiently annoyed about failing backup-MX servers for lots of different domains giving reports of type:

most common of which are rather misleading wordings about what is going on; that the server administrator has not listed allowed relay destinations into some file...