check invocation of send_mail_for_activity explicitly
check invocation of send_mail_for_activity explicitly

and stub out for tests which don't care

daukantas/factlink-core,Factlink/factlink-core,Factlink/factlink-core,Factlink/factlink-core,daukantas/factlink-core,Factlink/factlink-core,daukantas/factlink-core,daukantas/factlink-core