I have a verified domain using a DKIM. The DKIM was created by the email relay, added to my DNS, and verified by the relay. Once I got the EXM set up properly and was able to add a domain, Sitecore associated it with a different DKIM that is not verified. How to I setup my domain in Sitecore with the already verified DKIM?
In EXM, using Sitecore's Email Cloud Delivery service (EXM 3.4+), you have to use the DKIM Keys that are provided to you by Sitecore. This is how Sitecore recognizes that your domain is reputable.
You can find the DKIM keys in that screen by double clicking on the domain or by using the eyeball button.
From there, you should be presented a similar window to the image below where the new DKIM keys are supplied. You will want to have someone in charge of your DNS server records to update the DKIM for the domain in question and add these keys as a TXT Record. Also note, when making DNS changes, it can take as long as 72 hours for changes to take effect.
Once you have updated your domain keys, and Sitecore's Email Delivery Cloud Service recognizes the keys on the domain, you should see the DKIM box flip from a Yellow Triangle with an Exclamation Mark to a Green Check Mark.
Please note, this image is from EXM 3.3, but should be similar in looks.
I have a somewhat related issue with EXM 3.3. A few notes in case they help.
Support have stated that the DKIM information displayed in the domain verification screen is incorrect. From SC support:
Please note that your DKIM values should be like this: v=DKIM1; k=rsa; t=y; p=SOMEVERYLONGKEYVALUE
I believe "v=DKIM1;" was missing from the instructions on that screen
Also, the SPF record must be an exact match - you can't include additional domains in that SPF record the validation method doesn't understand the specification/syntax, it just looks for an exact match.