SMTP Service adjustments

If you are receiving your email by SMTP direct from the Internet and find that you are receiving an unacceptable amount of spam you can make the following adjustments to the SMTP service Properties

These dialogs are accessed from the Mailtraq Console, at Options | Services - SMTP Service, [Properties]

It is suggested that you ensure you have a stable mail flow before enabling these options, as they work by rejecting mail. You should be sure that you are receiving messages as expected before enabling them - which is why they are not enabled by default. See below*

 

Verify Return-Path has valid MX or A record
If this is checked, Mailtraq will lookup the MX and A records of the domain specified in the FROM: statement (which is the message's Return-Path). If Mailtraq cannot resolve this name, it will refuse the message. This is both because it cannot discharge its responsibilities, and because the message has probably been sent as part of an attack or is SPAM.

DNS Servers
In the DNS Servers Field enter a list of Domain Name Servers that Mailtraq can use when resolving the MX records.

 

 

---

 

Invalid or unresolvable HELO arguments

In SMTP, the HELO command is used by the sending host during an SMTP transaction to identify itself to the receiving host. SMTP does not actually require the HELO name to be the host's real name, or even to be in the correct format for a host name. It's extremely common, if not universal, for hosts sending spam to use fake HELO names.

Mailtraq rejects by default remote SMTP connections using local HELO arguments.

Mailtraq also allows you to reject messages with invalid or unresolvable HELO arguments by enabling the check boxes in this dialog box.

This dialog box is accessed from the Black Lists tab, at the
[Explicit Black Lists] button.

 

If you have problems with your emails being unexpectedly blacklisted see:
KB06082101 Messages returned marked 'Blacklisted' 

---

*Why doesn't Mailtraq load these settings by default?

In an ideal world, everyone would correctly configure their mail servers and these rules could be rigorously enforced. Unfortunately, not all mail servers are as easy to configure as Mailtraq, and there are many legitimate mail servers - perhaps one of your customers - that are set up with invalid HELO arguments, and so forth.

As these settings reject clients who do not conform to the rules, it is important that you understand the implications of using them. You need to weigh the risk of rejecting a few valid, but mis-configured, connections against the benefit of greatly reducing the amount of spam you receive.