My custom name instead of the topic name

[Yaro7619]

Hi. :bulb: Idea It would be nice to have the option to provide a custom name instead of a topic name, like in most e-mail clients.

Now, recipients receive an e-mail from a sender named: domain.tld/topic cn@domain.tld It would be nice to have format like this: Custom Name cn@domain.tld

https://github.com/binwiederhier/ntfy/blob/630f2957deb670dcacfe0a338091d7561f176b9c/server/smtp_sender.go#L115

:computer: Target components ntfy server