Allow different reply-to addresses

[riotbib]

Currently only mail addresses which are already included in the conversation may be sent mails to.

Allowing different reply-to address would enable sending mails to different mail addresses from the same authority, e.g. when those are mentioned in a paper letter.

You could include a test if the "new" mail address is known, using the same FQDN or mailserver than the previous one – to not enable spamming with your infrastructure.