As IL pointed out that is in 2nd Edition, there are some things that are generally accepted in PBEM unless otherwise stated.
Also, A transport CANNOT unload into multiple territories during combat. However, multiple trns can have different locations.
IE, if UK was attacking both Fin and WE and the only have 1 trn, they can’t unload 1 inf into WE and 1 inf into Fin. But if they have 2 trns then they could land in both, one trn for each location.
One of the PBEM Clubs has a Rules Clarification and FAQ for this one.
Here are some differences that may come up between 2nd Edition and 3rd Edition.
2nd Edition
W Can connects to E can sz
1 hit Battleships
You cannot retreat anything from an amphib assualt (including planes)
Subs can retreat (but not submerge)
If you bought ships but the enemy occupies your sz then you can’t place them and you lose them
3rd Edition
W Can does not connect to E can sz (so you can’t do that W can to WE move)
2 hit BB (although many people may still request keeping them 1 hit)
You can retreat planes from amphib assualts
Subs can retreat or submerge
You can place new naval units in an occupied sz
Most people I’ve played here play by 2nd Edition Rules. If you are familiar with the CD game from 1998 there were other options that some players also use. Usually the ruleset is clarified prior to playing. But most people I’ve encountered play 2nd Ed, which would be the ruleset from the Board Game anywhere from the early/mid 80’s to about '98.