Since a week or two, the GameSpy server for the Cossacks I series doesn't allow you to create games anymore, though you still can join the lobby chat.
I'v talked to cdv SoftWare Entertainment ( USA) about it and here is a quote from Bill 'Von' Smeed, QA/Community Manager/Tech Support :
"I'll check on my end, although we (cdv USA) have had nothing to do with any game servers for any games, as the games developers always maintain and own the servers for their own games, and multiplayer issues were always handled by cdv AG (Germany) in the past, but they no longer offer support."
So untill we get more information from cdv (USA or Germany/HQ) I suggest you either use GameRanger or the GSC.net Server.
The GSC.net server is only available for people with the Back To War (1.35 + ) version and it requires a gamebox ID.
For those that do not longer have their gamebox ID, you can obtain one @ http://www.americanconquest.de/key/english.php
The page is for American Conquest , but the GameBox ID's generated can also be used to access the Cossacks GSC.net Server.
Simply register with a valid email, follow the procedure to obtain a key and a mail will be sent to you with a new gamebox ID. For those that do not receive a mail, kindly check your spam folder.
Once you obtain a key, you can access the GSC Server by filling out the profile page in the Multiplayer Tab of the Cossacks I Main Menu.
For those that want to use special characters in their name ( eg [CLAN]^_^Tags^_^ ) but have already registered their name, you can use this little tool made by [BoB]Sponge on http://cossacks-portal.com/ to delete your old account and set up a new name. The tool has been tested with the German version of Cossacks. If it doesn't work for you, you can manually delete or rename the "C:\Program Files\Cossacks - Back To War\Internet\Cash\lgdta.log" file.
Meanwhile I'll try to get more information whether this situation with GameSpy is permanent and if possible, ask GSC to put mods/admins on their Server and restore the Tournament Options on the GSC Server, though that last is highly unlikely to happen.
If you have problems joining/creating games on the gsc.net server, just leave a message below and I'll look in to it.