Well fastmail's servers are not in Russia, so they can just keep using SMTP without issue, it would only be the client in Russia who would need to tunnel his traffic to fastmail.
You're forgetting the SMTP server on the other end. If Fastmail SMTP servers can no longer relay messages from/to Russian SMTP servers, then Fastmail is no longer a viable email service for Russians communicating with each other, unless all of them were using foreign based email services.
I am not forgetting anything. It is indeed true that fastmail is broken for Russians in Russia. And trying to tunnel out to fastmail just to mail back in to Russia makes little sense.
Also broke are all Russian email users who have to send to or receive from the free worlds fastmail accounts. Would seem this is just Russia damaging Russians.
