FAQ: MailHurdle

Issue

What are some common questions and issues that I should be aware of when using MailHurdle?

Solution

How do I deploy/implement MailHurdle?

For information about deployment and configuration, see the MOS Configuration Guide and the Message Server/RazorGate Administration Suite online help.

What known hosts do not retry, or have unacceptably long retry delays?

The following list contains known sites that do not follow RFC conventions for SMTP retries. This list is enabled and system-maintained by default, but can be disabled by de-selecting the Allow Known Good Mailers option on MailHurdle's Advanced page (Home > Antispam > MailHurdle  > Advanced within the Administration Suite). You can also manually add the hosts listed here to the appliance's allowed senders list (Home > Antispam > Allowed Senders) or to a delegated domain's allowed senders list (Home > Domains > Allowed Senders) as well, to exempt them from MailHurdle processing.

Updates to this list are available periodically and should be scheduled on the Antispam Updates page (Home > Antispam > Updates) using the Update all rule groups every week option.

12.5.136.141/32    # Southwest Airlines (unique sender, no retry)

12.5.136.142/32    # Southwest Airlines

66.135.209.0/24    # Ebay (for time critical alerts)

66.135.197.0/24    # Ebay

66.218.66.0/24      # Yahoo Groups servers (common pool, no retry)

66.218.67.0/24      # Yahoo Groups servers (common pool, no retry)

204.107.120.10/32 # Ameritrade (no retry)

205.206.231.0/24  # SecurityFocus.com (unique sender per attempt)

207.115.63.0/24    # Prodigy - broken software retries continually (no delay)

207.171.168.0/24  # Amazon.com

207.171.180.0/24  # Amazon.com

207.171.187.0/24  # Amazon.com

207.171.188.0/24  # Amazon.com

207.171.190.0/24   # Amazon.com

213.136.52.31/32   # Mysql.com (unique sender)

217.158.50.178/32  # AXKit mailing list (unique sender per attempt)

Why does it appear that mail gets delivered out of order (i.e., time sequence)?

If you receive an email from someone and it gets delayed (say the sending server delays the email retry for 30 minutes), and the same person sends you an email 5 minutes after the first email, you will receive the second email first, and the first email 25 minutes later, when it's retried by the sending server.

This is because the first email, after the default 5 minute delay (i.e., the Initial-Deny option on MailHurdle's Configuration page, Home > Antispam > MailHurdle > Configuration) moves to an Initial-Active state and, while in that state (by default 12 hours) subsequent mail from the same sender gets delivered without delay. Meanwhile the first mail must still wait to be moved to the Active state, and that does not happen until the retry for it is received.

How can I receive email immediately from a user who has never sent me email before?

If you know you are going to receive email from a specific user who has never sent you email before, you can prime the system by having the user send you two emails, 6-7 minutes apart; this assumes an Administrator has not changed the value of Initial-Deny from the default 5 minutes. Priming allows all future emails from that sender to make it through MailHurdle without a delay.

Why do I get multiple copies of the same email delivered 5 to 30 minutes apart?

This can occur if an email message is sent to your email address and to a mailing list to which you belong (for example, joe@example.com and sales@example.com — where joe is a member of sales@example.com). The problem occurs when previously the sender has sent an email to only one of the two addresses.

In this example, if the sender previously sent an email to joe@example.com, then there will be no delay for the email addressed to joe, but there will be a delay for the same email addressed to sales@example.com, and joe will receive the group email after it has been retried by the sending server.

Why do mailing list messages continue to be delayed, even though I've received list email before?

Some mailing lists use a technology called VERP (Variable Envelope Return Path). If your mailing list uses this technology, mail from that mailing list will be delayed. To bypass this problem, you can safelist the domain from which your mailing list emails are sent by adding it to the allowed senders list (Home > Antispam > Allowed Senders).

Why does someone sending me an email get delivery errors?

Some mailers are incorrectly configured and will send back any error message (for example, the error code that MailHurdle uses) to the sender of the email. Obviously, this can be annoying to the sender. For sites where this occurs, be sure to add the domain to the allowed senders list (Home > Antispam > Allowed Senders), so they will no longer be affected by MailHurdle.

What else is available besides MailHurdle to combat Spam?

Mirapoint provides both built-in antispam features as well as licensed features.