My idea is:
When no Reply-To address is configured, Mautic should omit the Reply-To header if it would simply duplicate the From address. Explicitly configured Reply-To addresses and those that differ from From should remain unaffected.
I think these groups of people would benefit from this idea:
Anyone sending emails or newsletters through Mautic, particularly those using no-reply addresses. For example, including Reply-To: no-reply@example.com when the From address is already the same looks unnecessary and potentially confusing.
Why I think they would benefit from this idea:
It would keep email headers cleaner without changing how replies work. According to RFC 5322, when Reply-To is absent, replies are directed to the From address by default.
Any code or resources to support this idea:
The relevant logic appears to be in MailHelper.php.
Related discussions: #14040, #15722, #16164.
Are you willing to work on this idea?:
Potentially, yes. I’d be happy to help prepare a pull request if the maintainers agree with the proposed change.
What skills and resources do you need to explore this further?
Guidance from the maintainers on the proposed behaviour, along with help reviewing and testing the implementation.