Mail Between Factions?

Hi all,

Apologies for the lack of knowledge, I have just got into WoW and started off in Wotlk Classic. Just curious if you are able to mail items/gold to your alt characters on the same realm if they are in a different faction.

Aliance to Horde & vice versa.

From my understanding you can currently in retail, however couldn't find much online anout Wrath Classic.