Hi,
We have been using Mailenable for a number of years as a backup MX server with it acting as a smarthost for our domain forwarding email to our main server.
This has worked fine for some time, but a user recently reported that an email they sent to another user on our domain was rejected with the following error " 551 This mail server
requires authentication before sending mail from a locally hosted domain. Please reconfigure your mail client to authenticate before sending mail.". The sending user had sent the email via a local SMTP server, which had not been able to contact our main server at the time so sent it to our Mailenable server instead and resulted in the above message.
Email sent from external domains are accepted (SPAM checks permitting) and forwarded to our main server as expected.
Unfortunately, I'm not sure how long this has been happening for as its mostly unusual to receive feedback from users. We was running v7.04 standard edition (freeware), and I have upgraded to v7.09 but still receive the same message.
Am I missing a tickbox somewhere? I don't want to enable the "allow relay for local sender addresses" as I believe that would open our server up to spoofing attacks.
Any advise would be appreciated.
Kind regards,
Dean
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