- They cannot send goods to each other.
- They cannot send military units to each other.
- They cannot raid each other - military and piracy.
- They cannot trade with each other.
- They cannot spy each other.
- They can join the same alliance(s).
- They can use the in-game messaging systems - the in-game message, the chat, the alliance forums, with each other.
- They can have cultural treaties with each other.
- They can donate on same island(s).
- They can be friends with each other.
Briefly, as long as there is no fleet contact between the involved accounts, everything should be fine.
Raids count as fleet contact.
