Suggestion: Enable SMTP authentication for local delivery

Question asked by Roger - 8/26/2025 at 12:15 AM

Answered

Hello everyone

I have a problem where, when the “Enable domain SMTP authentication for local delivery” log setting is enabled, a customer on my mail infrastructure cannot receive messages from prospective customers who are in the staging process. I create the tenant and set up the email accounts individually. It can easily take a month before the changeover is complete, as the customer is still receiving training, detailed settings for calendars, etc. are being made, etc.

During this time, this new customer cannot send emails to other domains on our SmarterMail instance because they think that relaying is taking place here. I suggest that an option should be activated globally for this setting so that accounts in a certain status are excluded from this setting. Alternatively, this setting could perhaps be configured individually at the domain level, which would also solve many problems.

Thank you and best regards

5 Replies

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Zach Sylvester Replied

8/26/2025 at 3:49 PM

Employee Post Marked As Answer

Hey Roger,

In this case, I’d recommend adding their old server’s IP to your whitelist and checking Bypass SMTP Authentication. That should allow those emails to go through.

Please let me know if this resolves the issue. Just keep in mind that bypassing SmarterMail’s authentication protocol means that any mail from that IP could technically send as anyone on your server.

The best long-term solution would be to switch them over completely including DNS and have them start using the new mail server while you migrate data.

Kind regards,

Zach Sylvester

Software Developer
SmarterTools Inc.

www.smartertools.com

Roger Replied

8/27/2025 at 4:26 AM

Hello

I can't always do that. Most customers are using Microsoft 365 before they come to us.

Brian Bjerring-Jensen - VonBjerring GmbH Replied

8/27/2025 at 4:47 AM

You can also change the setting to use MX Record instead of local delivery...

Roger Replied

8/27/2025 at 5:47 AM

I do but this does not work in this constellation

Douglas Foster Replied

9/25/2025 at 6:42 AM

This problem is greatly simplified if you have an incoming gateway. The gateway can determine whether the message should be allowed or not, and then the gateway IP can be whitelisted on your mail store server. If the incoming gateway includes a customizable product like Declude / Declude Reboot, you should be able to handle any complication that your scenario creates.

SmarterMail + Declude/DR are both free, and SmarterMail provides support for a free gateway as part of your paid server license. MailsBestFriend helps with Declude/DR at reasonable rates. So the price is right. Using an inbound gateway improves security and performance.

More importantly, an inbound gateway can solve your problem in days, in response to your business priorities, instead of being dependent on the priorities and resource limitations of the SmarterTools development staff.

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