User ManualEmail Discussion Group User Guide ReferencesExample of a message sent to the ISP by's BRDS (Bounce Re-delivery System).

Example of a message sent to the ISP by's BRDS (Bounce Re-delivery System).

When a subscriber's ISP bounces back a message sent by the list owner via, the ISP (Internet Service Provider) is automatically sent a message by our BRDS (Bounce Re-Delivery System).

Example of email to ISP:

From: Double Opt-in Mailing List <>


Subject: Please allow our double opt-in email to your customer

Date: Mon, 18 Oct 2019 06:35:30 +0000

Dear Postmaster:

You all are blocking your customer's email, that they requested, from a double opt-in mailing list.

If your customer has set up their own blocklist, please let us know by clicking on the following link.

 We will update our database so that we don't send you any more messages like this one.

I know you are doing the best you can with all the spam out there, and that mailing lists can easily look like spam.

However, a small effort on your part can keep your paying customers happy :-)

Here's what your MTA machine said to our MTA machine.

   550 Spam detected

This happened when we tried to deliver the following newsletter(s):


The newsletter(s) is about:

   monthly opt-in newsletter for UK satellite TV users

You can read the blocked newsletter(s) at

It failed when we were trying to deliver messages to these subscriber(s):

Here's an example of the entire MTA log that we have on one rejection that your machine made.

2019-10-17 21:45:24 1P7b2H-0001JI-Fd ** F=<> R=dkim T=dkim_smtp: SMTP error from remote mail server after end of data: host []: 550 Spam detected

Our machine clock is set to UTC aka GMT time.

The best solution is to whitelist all of our IP Addresses, which are listed at

Please cut and paste all of our IP Addresses, so that you will not block future emails.

Or, if you all whitelist by the From Address, then the Envelope From Address(es) is:

And the Header From Address(es) is:

So depending on whether you use the envelope sender or the From Header, please use the appropriate address.

You all can contact us at via email at

 Or by telephone at 1-713-520-4500

Thank you.


p.s.  If you do not want to receive more of these messages, please click on this link

p.p.s.  We maintain a blog of feedback we have received from other postmasters at is owned and operated by

Internet Tools, Inc.
1302 Waugh Dr. #438
Houston, TX 77019 


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