We DK and DKIM sign where I work since some places look for DK and some look for DKIM. We don't sign all mail from the domain though; however, we are looking to start DKIM signing all mail from our domain in the near future. We are also hoping RFC 5617 (the adsp portion) becomes more readily accepted since DKIM is not as helpful if you can't say all my mail will be DKIM signed.

Hello !
We do sign with DK and DKIM for most of our mail domains. We have had no problems with the implementation.

My only recommendation is : TEST TEST and RE-TEST

There are lots of tools on the Internet to check if your signing is correct !

Cheers,
Frédéric

We sign all outbound mail with both DKIM and DomainKeys.

Yahoo currently only give you the 'signed' icon next to your message in the webmail interface if the message is signed with DomainKeys. When they start trusting DKIM-signed messages then we will drop DomainKeys and only keep DKIM.

A large percentage of our customers use Yahoo as their mail provider.

I'll second the "test thoroughly" sentiment, using Ironport it is easy to use one mail account for testing signing. Combine this with a 'T' flag in your DNS record and it should be easy going.

For helping verify your messages, do a search for 'dkim reflector'.

We sign all outbound mail with both DKIM and DomainKeys for all our domains. I test it with yahoo, gmail and some online tools like this http://www.myiptest.com/staticpages/index.php/DomainKeys-DKIM-SPF-Validator-test

Serious guys must use DKIM (DK) and SPF... i think.