Re: [mailop] Send emails over O365 to Google with a specific domain are rejected

[Al Iverson via mailop]

Domain reputation blocks at Gmail are more common nowadays than in years past.

Suggestions:
Make sure all mail passes SPF and DKIM, especially DKIM. Has to be a
DKIM signature for dnn.de, not the default "onmicrosoft.com" domain
that O365 will use by default.
Submit a request for reconsideration here:
https://support.google.com/mail/contact/gmail_bulk_sender_escalation?visit_id=638269633865177067-1793378121&rd=1

Learn more about that form here:
https://www.spamresource.com/2022/01/gmails-sender-contact-form-what-and-why.html

If MS is using IPv6 to send the mail to Google, you might be in an
extra difficult spot. Not everybody agrees/believes this, but in my
experience Gmail is more quick to block IPv6-sent mail; they're more
stringent about what they might let through versus IPv4. I can't
imagine that's something you can control, but, hey, if I'm wrong and
it is, it's worth checking.

You're on the right path with GPT. Might also want to make sure you've
got a DMARC policy in place with p=quarantine or reject. If you really
have no bad history with this domain, it could just be that Gmail is
suspicious given a lack of history.

If you REALLY get nowhere, it might be time to consider moving off of
O365 and onto some other infrastructure for corporate mail. Just
because you don't really have enough control over the infrastructure
levers here.

Cheers,
Al Iverson

On Sun, Aug 6, 2023 at 12:02 PM Oliver Kirchel via mailop
 wrote:
>
> Hello,
>
> I am a postmaster for a German media company and for the last three weeks I 
> have had the problem that emails from a certain domain (dnn.de - hosted at 
> O365) are being rejected by Google (suspects your message is spam and 
> rejected it). Emails from the domain that are not sent via the O365 
> infrastructure arrive. I then configured the domain at 
> https://postmaster.google.com/ and the statistics I see there actually look 
> quite good. Has anyone else had such an experience or is there someone from 
> Google reading this who I can talk/write to?
>
> Thanks Olli
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-- 

Al Iverson / Deliverability blogging at https://www.spamresource.com
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Re: [mailop] Send emails over O365 to Google with a specific domain are rejected

[Otto J. Makela via mailop]

On 8/7/23 03:06, Al Iverson via mailop wrote:


If MS is using IPv6 to send the mail to Google, you might be in an
extra difficult spot. Not everybody agrees/believes this, but in my
experience Gmail is more quick to block IPv6-sent mail; they're more
stringent about what they might let through versus IPv4. I can't
imagine that's something you can control, but, hey, if I'm wrong and
it is, it's worth checking.


I concur, Google seems to think that if you are using IPv6 for transport
you must be Teh Master of Teh Internet™, and it'll be trivial for you
to get every single detail right in your messages.

Then again, I can easily see how spammers would use IPv6 addresses to
snowshoe their spam insertion.
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Re: [mailop] Send emails over O365 to Google with a specific domain are rejected

[Gellner, Oliver via mailop]

On 09.08.2023 at 10:05 Otto J. Makela via mailop wrote:

> On 8/7/23 03:06, Al Iverson via mailop wrote:

>> If MS is using IPv6 to send the mail to Google, you might be in an
>> extra difficult spot. Not everybody agrees/believes this, but in my
>> experience Gmail is more quick to block IPv6-sent mail; they're more
>> stringent about what they might let through versus IPv4. I can't
>> imagine that's something you can control, but, hey, if I'm wrong and
>> it is, it's worth checking.

> I concur, Google seems to think that if you are using IPv6 for transport you 
> must be Teh Master of Teh Internet™, and it'll be trivial for you to get 
> every single detail right in your messages.

Another explanation might be that Google wants to introduce additional security 
controls without breaking all kind of existing communications. So they enforce 
those controls primarily for new remote endpoints. When you try to send 
messages to Google from an IPv4 address that Google has not received 
connections from before, you might also be subjected to requirements which 
other servers that send emails from their IP addresses since years do not (yet) 
have to fulfill. And since most IPv6 addresses did not send emails multiple 
years ago, they can all be considered new.

--
BR Oliver


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Re: [mailop] Send emails over O365 to Google with a specific domain are rejected

[John Levine via mailop]

It appears that Otto J. Makela via mailop  said:
>I concur, Google seems to think that if you are using IPv6 for transport
>you must be Teh Master of Teh Internet™, and it'll be trivial for you
>to get every single detail right in your messages.

They've said for a long time that all mail to them over IPv6 has to be
authenticated. This should not be news to anyone.  If you can't do that,
use IPv4 until you can.

What has changed lately is that they have also gotten pickier about
unautnenticated IPv4 mail.

I do wish they'd figure out how to get rid of the plague of chatty B2B spammers
using throwaway gmail accounts.

R's,
John
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