Sending Email Errors

Overview

Our email servers may direct you to this page for more information regarding an error. Please see below for the message that matches the error you have.

Error Codes

CA1

This suggests that you are sending email through smtp.aa.net.uk with authentication. but the system has detected a high amount of invalid email addresses that the account is sending email to. Feature added December 2013. There are 2 main reasons for this:

Possible Compromised Account?

The account may be compromised and a third party may be using your account to send lots of junk email. Typically a junk sender will send lots of emails and many will be to invalid addresses. To help prevent spam we have blocked the account from sending further email. Please contact support for more details, we would request you to change your email password before we unblock the account.

Sending to a Mailing list with invalid addresses?

It may be that the account has been blocked as you have a mailing list that you send email to that has many invalid email addresses. When you send email to invalid addresses you would get a bounce back message. It is normal practice to then remove these invalid email addresses from your databases. In this case, ask Support to unblock the account.

CA2

An IP address has been blocked from sending email through smtp.aa.net.uk due to it sending a number of high spam scoring messages in a short period of time.

BO1

This means that we have blocked sending of a non-delivery report type message. This would be an email, typically from a customer server, that is a bounc eback message. Rather than rejecting the incoming message at SMTP time, the customer mail server has accepted the incoming message and then decided that it was now wanted, and generated a new email back to the original sender saying that the message has not been delivered.

We don't allow sending of bounces back messages due to backscatter problems. -ie, most of the time the message being rejected is spam, and so a reply to the spam just means that email is being sent to an invalid address anyway.

In these cases, please configure your email server to reject mail at SMTP time, or to send messages by MX records rather than relaying through smtp.aa.net.uk.

We catch this by matching a null sender address, ie the sender email address is <>, and a list of known subject lines that are bounce back messages eg:

DELIVERY FAILURE
Delivery Notification: Delivery has failed
Delivery failure: Returned to Sender
Message you sent blocked by our bulk email filter
Delivery Status Notification
Mail System Error - Returned Mail
Mail delivery failed: returning message to sender
Returned mail: User unknown
Returned mail: see transcript for details
Undelivered Mail Returned to Sender
failure notice
Permanent Delivery Failure
Returned email
Transient Delivery Failure
There may be others...