OpenPGP Unverified signature from DH - Thunderbird Enigmail

Could someone explain what I’m doing wrong?

I want my Mozilla Thunderbird client to verify the OpenPGP signatures in messages from DreamHost, but each e-mail I get from DH has an error in a yellow box above the message as follows:

I use the Enigmail extension. Researching the problem, I found this wiki page on the DH wiki: From there, I imported the support.asc key as the article suggested. I can see this imported key from within OpenPGP in Thunderbird.

How do I get it to verify the signatures from DH e-mails?

Does anyone else have this problem?