fix: use From address for reply-to-sender-only on mailing list emails

[GretaD]

fixes: #11089

🤖 AI (if applicable)

• The content of this PR was partly or fully generated using AI

[ChristophWurst]

Does this break any of the existing flows? I'm skeptical because replyTo is now generally unused.

[GretaD]

Does this break any of the existing flows? I'm skeptical because replyTo is now generally unused.

I tested reply all, and its the same as on the main branch. I tested an email with a couple of recipients but without a mailing list, and it works well too.

[ChristophWurst]

Test with an email that has an actual reply-to header. That's the case where it actually makes a difference.

[GretaD]

Test with an email that has an actual reply-to header. That's the case where it actually makes a difference.

all good

[ChristophWurst]

Tested and breaks the legit reply-to case of a multi recipient email.

How to test

1. Send an email to three recipients and use another reply-to address
2. Open that emails as recipient in Mail
3. Click Reply to sender

main: reply-to address is used ✔️
original sender is used ❌

The list condition needs a dedicated check. Only for lists it can be ambiguous if Reply to sender uses the reply-to (list) or original sender. Gnome Evolution shows a dialogue for this case.