This article applies to:

• Trustwave MailMarshal (SEG)

Question:

Why should I not send e-mail notifications to Unsolicited Commecial E-mail (UCE or spam) senders?

Information:

1. The primary reason not to send notifications back to senders of Unsolicited Commercial E-mail (UCE), also known as spam, is that these messages are also unwanted email (sometimes known as "backscatter"). Even when the return address is deliverable, it is nearly always unrelated to the sender.
   • You may find that if you send such messages your server will be listed for blocking by some anti-spam organizations. 
2. E-mailing notifications back to senders of spam also poses the risk of over burdening the MailMarshal Sender service.
   • Often, senders of UCE use short lived or invalid domain names. MailMarshal will attempt to deliver notifications addresses for up to 72 hours before returning a Non-delivery Report (NDR) for the notifications. As the quantity of notifications that MailMarshal attempts to deliver grows, the Sender service will have fewer and fewer threads available for delivering legitimate messages and will eventually become backlogged. Once the sender service is backlogged, it is not uncommon to see delays of hours or even days for legitimate e-mail messages.

For both of the above reasons, Trustwave strongly recommends that MailMarshal not be configured to send administrative notifications back to the senders of messages thought to be spam.

Notes:

This article was previously published as:

NETIQKB35476