If you want your recipients to answer your emails to another account than the one used to send your messages, you can easily set a different reply-to address in YAMM.
This is useful if you want to send your mail merge from an account that is not monitored (like a 'no-reply' account), but still want to get feedback on your campaign from your subscribers and give them the possibility to reply, or if you are sending emails on behalf of someone else.
To do so, click on '+ Alias, filters, personalized attachments...':
Then specify another account in the 'Reply-to address' field:
Click on 'Back', and 'Send Emails'.
Once your recipient gets your email, he will be able to notice a different reply-to address from the sender's address: