Was there an unsubscribe link in the email? I've had other annoying services claim they didn't need it, but they were making money off their service, soliciting developers and were in violation of the CAN-SPAM Act.
Ouch, that's pretty unethical IMHO. Hopefully they add it, since the project owners are reading this thread.
On a side note, I've reported offenders to the FTC for violating CAN-SPAM, but the FTC just sends you a default reply that they don't look at individual reports for violations.