Apple Mail App woes...

Hello everyone...

I am having a simpel problem with my Appel Mail. Which I basically caused myself but am lost as to HOW to rectfy teh situation...

I have 6 accounts I use for work/personal emails via the Apple Mail app. A recipient of my email messages recently notified me tha tteh 'reply to" email address had a typo in it, the reply to email had an extra "S" in it hence they received a "bounce-back" message. It is from a "gee-mail" account.

Q1: Where would go within Apple Mail to attempt resolve this?

AND/OR

Q1.1 : ....could the problem be within the 'Gee-Mail" site, where I mistakenly entered my address incorrectly?

Any sort of guidance would be appreciated, thank you for reviewing my question.