Hmm ,whilst SETI say you should get v3.03 they
haven't said that it is blocked yet or that you must get v3.03.
From SETI front page
SERVER STATUS: Due to reaching our current maximum bandwidth allowed by the University, many connections to the server are being dropped. Please upgrade to version 3.03 if you haven't done so already, which will help reduce the load.
From SETI text only download page
Client Version Transition
As you may have noticed, the expected transition of the v3.0 clients did not take place on schedule. With the release of the v3.03 client which will be a mandatory upgrade for all users, the v3.0 transition was postponed. At the time of this note (2000-12-18) the moment of transition for v3.03 has not yet been set. In the meantime, if you see a version 3.03 client for your platform, you should be upgrading. To verify your client version:
Looks like we can wait until the transition date

,BTW their servers are likely to get bogged down at that point so it would be a good idea to download the v3.03 client now ready for the date.