@farmboy It is always a good idea to check for the email/game ID information in the PBEM settings after loading a savegame. Usually the email and gameID details are saved with the savegame.
What you experience should not be a question of mixing up details but likely replacing “old” details with those of the “new” savegame.
As you have noticed savegame files get bigger the longer a games lasts, as it is always the complete game history that is saved with the file. So be sure to take the time to completely load the savegame.
You should be safe, then.
When you start TripleA without opening a savegame the game points to the map that you had chosen to play lately:

Now when you load a savegame, the loading procedure is over once the file you have chosen appears replacing the mapfile:

At that point you can be sure that all information has been loaded into the engine. However I recommend to verify the PBEM settings as mentioned above.