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TechGuy_007
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Exchange 2016 getting bounce backs from google

Exchange 2016 getting bounce backs from google:

mx.google.com gave this error:
[2601:40d:8001:dc00:5436:c102:4af2:5c68] Our system has detected that this message does not meet IPv6 sending guidelines regarding PTR records and authentication. Please review https://support.google.com/mail/?p=IPv6AuthError for more information . f10si1906405ioi.62 - gsmtp

I cannot figure this out for the life of me. If it's as simple as a radio box I might just cry. lol
* IPv6ExchangeGoogle

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Adam Brown

8/22/2022 - Mon
ASKER CERTIFIED SOLUTION
Edward Pamias

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Edward Pamias

Of course the information above is not for your site but maybe it will help you resolve your problem.
Adam Brown

You basically need to contact your ISP and ask them to add a PTR record for your mail server's IP address that matches either your domain or your mail server's name. Essentially, Google's system is doing a reverse IP lookup on your IP and finding the PTR record doesn't match your domain, then refusing the connection because they expect it to be spam.
Jackie Man

Agreed

1. Goto http://www.dnsstuff.com/tools

2. Under DNS Lookup, type the full URL your mail server hostname... say mail.domain.com

3. In the pull down menu of "Choose a DNS Record type" select PTR and click the blue triangle button next to the input field of the full URL your mail server hostname.
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rwheeler23
TechGuy_007

ASKER
I called the ISP and they had the wrong static ipv4 and ipv6 information. I had them setup reverse DNS. I'm waiting the 24-48 hrs to see if it is resolved.
Jackie Man

You should be fine after reverse DNS setup.
TechGuy_007

ASKER
Unfortunately. The reverse DNS was setup, but I am still experiencing errors.
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Jackie Man

http://www.dnsstuff.com/tools

Post back the results on running the tool as mentioned in my previous comment.
TechGuy_007

ASKER
Target      smtp.stealthmgt.com
Timeout Value      1 (default)
Your Overall Score      Lookup failed
Jackie Man

Did your ISP charge you for Reverse SMS lookup?

Your result Indicates reverse DNS lookup is not yet made.
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TechGuy_007

ASKER
no
Jackie Man

Then, they are not obliged to help you at all. Setup of Reverse DNS lookup is not free as a lot of re-coding work at ISP side needs to be done.
TechGuy_007

ASKER
the ipv4 is good to go. the ipv6 is not. i've checked the records on MXtoolbox.com and it will show for the a record but not the AAAA
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Jackie Man

There is nothing can be done on the matter and your only way out is to discuss with your ISP.
Jackie Man

Google will not entertain you just to give you an exception for no proper reverse DNS setup and they will just think that you are a SPAM source.
TechGuy_007

ASKER
Yeah, I called the ISP again and am awaiting a callback from tier 2
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TechGuy_007

ASKER
ptr record is setup but bounce backs are still occuring
Jackie Man

http://www.dnsstuff.com/tools

Post back the results on running the tool as mentioned in my previous comment.
TechGuy_007

ASKER
@Jackie_man your tool keeps failing. But when i run a reverse lookup on mxtoolbox, it shows my ptr being correct.
error-1.png
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Adam Brown

All of this is a lot easier to deal with if you use a cloud based spam filter and send your outgoing email through that. They generally take care of the reverse DNS and SPF issues. Also, do you have SPF set up on your public DNS to include your IPv6 record?
TechGuy_007

ASKER
I have it running through barracuda cloud spam filter. i think i have it figured out FINALLY.
Adam Brown

Just a note here...Based on google's guidelines, not having an SPF record or DKIM configured will cause the issue you see here. You'll also need to make sure you aren't black-listed. That said, sending mail out from Barracuda is a better solution, since it provides you with better mail security.
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