I'm currently trialling HoudaSpot and have had a few issues dragging search results to DevonThink Pro Office. DTPO supports email archiving, you can simply drag email messages from the Mail app window into DTPO and the message, attachments and any tags are inserted into the DTPO database.
I had used HS to search my email and once I had found what I want I dragged the results into DTPO. The tags make it, DTPO sees the MailTags tags and it sees the text of the message but doesn't index it like it does from Mail so I can't search for the contents.
DTPO reports that the emlx file is an unknown format although it will display it correctly. Messages dragged from Mail app appear as eml file kinds and are able to be searched.
DevonThink have a plug-in for Mail that helps the transfer of mail into DTPO and I wondered whether there was anything that could be done to allow dragging mail from HS into DTPO?
I've posted a similar question on the DevonThink forums hoping that I'll get an answer one way or another.
It would be good to see HS working with DT as HS provides a great way to find content that can be put into DevonThink.