Qpsmtpd:resolvable fromhost

Qpsmtpd#Plugins

NAME

resolvable_fromhost

SYNOPSIS

Determine if the from host resolves to a valid MX or host.

DESCRIPTION

The fromhost is the part of the email address after the @ symbol, provided by the sending server during the SMTP conversation. This is usually, but not always, the same as the hostname in the From: header.

resolvable_fromhost tests to see if the fromhost resolves. It saves the results in the transaction note resolvable_fromhost where other plugins can use that information. Typical results are:

 a  - fromhost resolved as an A record
 mx - fromhost has valid MX record(s)
 ip - fromhost was an IP
 whitelist - skipped checks due to whitelisting
 null - null sender
 config - fromhost not resolvable, but I<reject 0> was set.

Any other result is an error message with details of the failure.

If resolvable_fromhost is enabled, the from hostname is also stored in resolvable_fromhost_host, making it accessible when $sender is not.

CONFIGURATION

reject < 0 | 1 | naughty >

If reject 1 is set, the old require_resolvable_fromhost plugin behavior of temporary rejection is the default.

 resolvable_fromhost reject [ 0 | 1 | naughty ]

Default: 1

reject_type

 reject_type [ perm | temp ]

Set reject_type perm to reject mail instead of deferring it.

Default: temp (temporary, aka soft, aka 4xx).

EXAMPLE LOG ENTRIES

 80072 (mail) resolvable_fromhost: pass, googlegroups.com has MX at gmr-smtp-in.l.google.com
 80108 (mail) resolvable_fromhost: pass, zerobarriers.net has MX at zerobarriers.net
 80148 (mail) resolvable_fromhost: pass, uhin.com has MX at filter.itsafemail.com
 86627 (mail) resolvable_fromhost: palmalar.com has no MX
 86627 (mail) resolvable_fromhost: fail, palmalar.com (SERVFAIL)

AUTHORS

2012 - Matt Simerson - refactored, added: POD, tests, reject, reject_type

2002 - Ask Bjørn Hansen - intial plugin

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