topic Re: outbound email being received multiple times in Email

outbound email being received multiple times

Blundell — Mon, 13 Mar 2023 11:55:52 GMT

Hi all.

Someone in our Sales team sent an email via our Exchange server to over 200 recipients(!).

The recipients are now reporting a week later that they are still receiving copies of the email.

There is nothing listed in our Exchange server outbound queue.

We send our emails via relay.plus.net using smtp.

Any idea how I can stop the emails?

Cheers

Re: outbound email being received multiple times

Townman — Mon, 13 Mar 2023 12:35:35 GMT

Hi, A warm welcome to the forums.

It would be helpful to clarify some of the detail provided - are you saying that...

You run your own in-house exchange server on your own equipment in your local network connected to a Plusnet broadband service?
You are using relay.plus.net as a smart relay?

For those persons reporting receiving multiple copies...

Who are their mail providers?
Are the email addresses (which your organisation sent to) end points or auto redirected via some third party?
Is there any commonality in their email client?

There have been a number of users who use various middle men to host their domain name (but not their email service) reporting that their end mailbox receive multiple copies of the same email. There is some empirical evidence that such third party forwarding services are failing to recognise successful message forwarding and are retrying multiple times.

There are a lot of resources on the internet describing the causes of email duplication, many of them involve auto forwarding services and transmission errors in such.

Re: outbound email being received multiple times

Blundell — Mon, 13 Mar 2023 14:51:01 GMT

Hi Townman.

Thanks for the reply.

The answer to point 1 is yes, we run an Exchange server and use relay.plus.net as a smart host.

The email was sent on Wednesday. On Thursday, recipients were complaining of multiple emails but there was nothing pending in our smtp outgoing queue. I restarted the server anyway. They continued to receive them over the weekend so I'm presuming it's getting repeated somewhere 'out there' as opposed to on our email server.

I'm not sure about the other points. I have asked a few recipients if they can answer them.

Thank you for your help.

Re: outbound email being received multiple times

Townman — Mon, 13 Mar 2023 16:24:06 GMT

It is not likely to be on your exchange server not the Plusnet outbound relay service. It is more likely to be where the target addressed is not hosted, but is in fact a redirection service.