Maximum Header Lines

Articles and documents provided by support staff covering Mailtraq features and general operation.

Maximum Header Lines

Postby Susan Bunbury » Tue Feb 26th, 2008 10:28am

A common characteristic of spam are large numbers of header lines. Mailtraq caps the number of header lines at 150.

Mailtraq 2.12 (from build ) allows you to adjust this number to suit your environment,
at the SMTP Service | Abuse-tab. See

This page explains how to upgrade your Mailtraq to access this facility if you need to.

Users can unexpectedly hit this cap if they have very large numbers of recipients in emails they are sending.
You may become aware of this problem by receiving a Delivery Report (Failure) similar to this:
While talking to [] your message:


couldn't be delivered to the following recipient(s):

for the following reason(s):

550 message header was 160 lines -- check header for corruption or loop

If you have any queries regarding this notification, please
write to

In general it is better practice to use Mailtraq's Mailing List services to distribute large numbers of emails, rather than simply CC'ing them
See &
Best wishes,

Sales and Initial Support
Enstar Mailtraq
User avatar
Susan Bunbury
Mailtraq Enstar Sales and Support
Posts: 359
Joined: Mon Aug 22nd, 2005 3:09pm
Location: CT, USA

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