In my real-life situation I am using gmail to handle email.
Different servers, so no affect.
It really depends on who/what/where, you’re doing this redirect. In most cases (99%) a redirect will redirect ONLY the http (or possible https) traffic, thus not affecting MX (or mail) records.
I include this caveat because there was once a hosting company (they got bought out) that had a “clone this domain” button that would also do some weird magic that not only created an http redirect but also created email aliases (or something) as well.