the next 5.5beta will fix domainkey issues as well.. wait for the final version which should go in at the end of july from what the devs have told me. they have a big show i believe coming up.
i honestly was upset with smartermail until we fixed our dns... it then improved our delivery rates by like 1000% we can now deliver 100k + messages an hour. then i was upset... when i contacted them for support.
the techie went above and beyond his duties... he even installed the marketing software we use to test if it was causing the bugs or smartermail. we probably worked on the issue for several hours for several days each... then we found the issue. he passed on all our errors to the dev team. it was great!
with other companies we often have to beg for them to pass the bugs onto their devteams... i often get "well maybe we'll pass it on to dev" then i have to open a second ticket bitching to have it passed on to devs... its inefficient. but with smartermail they seem to work together well as a company... so let the bug testers test the stuff out..
id hate to see you install software and lose like 10k $ in productivity or hours of time.