Cannot Receive Emails from External Senders

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Article ID: 170703

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Updated On:

Products

Email Security.cloud

Issue/Introduction

You are not able to receive emails from outside senders. Moreover, emails from the same sender do not show up in Track and Trace searches also.

Cause

Connection Level Email Delivery Issues on the Sending Server side

Resolution

If an external senders sends an email to a registered user on one of your domains that is provisioned with Symantec.Cloud Email Security, it should normally get delivered to your inbound routes within a few seconds.

 

Sometimes you may notice that an external sender claims to have sent an email that does not reach your server and it is not visible in Track and Trace either.

 

When it comes to Track and Trace, the rule of thumb is this: If an email is not visible in Track and Trace, chances are that it did not enter our infrastructure. This means that the email had an issue before or at the connection level.  Failures at those levels are not recorded in Track and Trace.

 

There could be several reasons why an email failed at the connection level:

  1. Your MX Records are not pointing to the provisioned cluster you should be using.
  2. You may have the MX Records in reverse order.  Here is the normal / recommended order:
    • 10 clusterXX.xx.messagelabs.com
    • 20 clusterXXa.xx.messagelabs.com
  3. The sending server may be hitting the MX Records in reverse order. They should hit / connect to the priority "10" MX Records and not the priority "20"
  4. The sending server's IP Address is blacklisted
  5. The sending server's IP is subjected to Rate Limiting and it is throttled.  Meaning we have seen a considerable amount of spam from the sending IP and we are limiting the number of connection from this IP in a given amount of time.  This happens mostly when a client acquires a new IP which was abused by a spammer before the acquisition. 

If you have verified the first 3 reasons mentioned above, please request verbose SMTP logs from the sending server side for the failed email attempts. Open a Support Case with us and share the logs. Once we have the information available, we will be happy to investigate and advise accordingly as the case may be.

Note: Apart from these reasons above, it's possible the sender didn't intend to send the mail to the specific recipient (like Bdy to), so check the sending server log as well.