gmail, yahoo, maybe others requiring DKIM?

[homerdog]

A bunch of my clients started having emails rejected by gmail and yahoo in the last 48 hours. The reason isn't entirely clear but the bounceback messages indicate that the messages are possibly being rejected for lack of DKIM on the sending mail server (Microsoft in my case). Now I'm working with Microsoft and my registrar to add DKIM to all my clients' domains but this is taking forever. Has anyone else had this problem recently? It seems to mostly impact users who send newletters with dozens to hundreds of recipients, but some users are having single recipient messages rejected (nevermind this domain's spf record had been lost for some reason).

I hope adding DKIM fixes this because otherwise it appears out of my control. That this happened with gmail and yahoo recipients at the same time is very odd.

 

[Davros]

How can i tell if emails i recieve at gmail have a dkim
ps: dont know if it helps but i can send an email from my microsoft email to gmail and it doesnt get rejected

 

[homerdog]

You can go here and enter the sender's domain and select "detect all selectors". You'll see at least 1 record (e.g. selector1) if the sender has DKIM.

DKIM Checker and Lookup Tool tools | EasyDMARC

Check your DKIM record and DKIM signature and determine if it’s valid. Simply enter your domain and click on the “Check DKIM” button.

easydmarc.com

It doesn't return anything for gmail.com or yahoo.com

 

[swaaye]

Yeah you definitely want to have DKIM and SPF set up. Gmail will also blacklist you temporarily if you hit some (not super high) volume cap they have.

An alternative is to use some Smarthost service to send outgoing messages. I've had to switch over to one in cases of temp blacklisting.

 

[homerdog]

One of the clients reported that all the emails were delivered around the same time I set up DKIM. But it seems like they got delivered a few minutes before I did that so I dunno.

 

[Malo]

I'd question why you have a service that you haven't already configured DKIM? It's basically required nowadays to get any chance of delivery to most big recipient domains.

 

[Davros]

Because he sucks at his job
That was a joke btw...

 

[homerdog]

I'd question why you have a service that you haven't already configured DKIM? It's basically required nowadays to get any chance of delivery to most big recipient domains.

https://learn.microsoft.com/en-us/m...entication-dkim-configure?view=o365-worldwide

You can choose to do nothing about DKIM for your custom domain too. If you don't set up DKIM for your custom domain, Microsoft 365 creates a private and public key pair, enables DKIM signing, and then configures the Microsoft 365 default policy for your custom domain.

Microsoft-365's built-in DKIM configuration is sufficient coverage for most customers

So I dunno how that's supposed to work for domains that aren't registered with Microsoft. But it's never been a problem until this week.

 

[homerdog]

After reading a bunch of documentation I'm more confused than when I started (how could Microsoft enable DKIM without access to DNS records?), but the problems are solved so I'll assume something I did fixed it

Okay thinking a bit more, maybe when MS says "custom domain" they mean a domain registered with them. This is the only way I can see this working. Maybe they have different terminology for domains registered with 3rd parties.