Krum has written an excellent plugin (KC s2M+WPML) that exposes s2's custom field labels and email texts to the WPML string translation table. Translation of the custom email fields works great. However new user emails are always sent as English, even though they have been translated in WPML. WPML support has identified the problem as an incompatibility in S2member. Below is their reply to me, can someone from s2 please assist.
"I can replicate the issue on my local server, it seems that it is a compatibility issue, the plugin s2Member is not listed at our compatibility list: https://wpml.org/documentation/plugins-compatibility, we may need the help of the plugin author to help us to know where is the code snippet that he use to send the mail for the clients, we have some documents to help sending translated emails: https://wpml.org/documentation/support/sending-emails-with-wpml/ we can also ask the client to join our Go Global program: https://wpml.org/documentation/theme-compatibility/go-global-program/ "