"reply" addresses the e-mail to me, not to the sender

When I reply to e-mails, eM appears to replace their e-mail address with mine (i.e., the reply is addressed to my e-mail, not theirs). This doesn’t happen for people in the cc field, and I haven’t set an e-mail alias or a different “reply to” e-mail address. How do I fix it?

I think this is intended behaviour - when you reply to a message the reply-to address should be yours, isn’t it?

Maybe I didn’t say this clearly enough. Let’s say my address is patrick@test.com. When I get a message from other@test.com and reply to that message, eM addresses the reply to patrick@test.com, as opposed to other@test.com. I’m pretty sure that’s not intended behavior?

Sorry, I misunderstood it first time. Now I see what is going on. Could you please send me one of the problematic messages saved as .eml? I need to analyze it and then send you further instructions. Thank you.