DNS Caching now causes Error: 602 Attempted to send the message to the following IPs:
Problem reported by ActorMike - 3/13/2024 at 3:49 PM
I've had enable DNS caching checked for years. After updating SM recently we started getting reports that messages were coming back with a 602 error. Turns out it is somehow related to the enable DNS caching setting as reported by Brian Bjerring-Jensen in the thread below.

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Matt Petty Replied
Employee Post
I see you have cert validation turned on and we recently made changes to that area. Have you confirmed these are DNS issues and not certificate issues? A lot of people are seeing 602's because of the certs.
Matt Petty Software Developer SmarterTools Inc. (877) 357-6278 www.smartertools.com
Zach Sylvester Replied
Employee Post
Hey Mike, 

Can you please try turning off Enforce strict certificate validation and see if the 602 errors are reduced?
Let me know if this helps. 

Zach Sylvester System/Network Administrator SmarterTools Inc. (877) 357-6278 www.smartertools.com
ActorMike Replied
I'm not asking for help, I am reporting a problem and how it was resolved. Seems like a bug to me.

Again, another user told me he resolved it by turning off DNS Caching. I tried this and left the Enforce strict certificate validation untouched, did a test and the email went through perfectly.

You have two separate users confirming the DNS Caching was the culprit.

There were no problems emailing this person until last week, now that DNS caching is turned off the emails went right through.

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