Sure - but that would be another thing to self-host - because I have at least 5 machines which need to send, and I have a dynamic IP address - so it would involve updating the MX records via DNS API for at least 5 sub domains.
To be honest, I'm a KISS kind of guy - not everything technical possible or imaginable is worthwhile. Especially if it's such a crucial part like alert monitoring. I want it done simple, secure, without caveats and keeping the complexity on the lowest level possible.
Even if it's a bit different. It's always nice to see what's out there. I will definitively look into it.