Others have has for years for a Reply-To field. Well, here is how I use mine and perhaps this will encourage the developers to add this feature as this is integral to my work flow.
Just like many here, I have had my own domain which is directed to my server.
In cPanel, I have a catch-all account where I have built a number filters. One filter says that anything that starts with “cqd-” goes to a specific email address firstname.lastname@example.org that I have designated for direct correspondence.
When I communicate with a person or a company, I give them a unique email address prefixed with cqd-, such as email@example.com
Since I have done this for over 20 years and everyone has been given a unique email address, if I receive a piece of spam, I can see where they got my email address.
So, let’s use Sony as my example. If I get a piece of spam sent to firstname.lastname@example.org, then I know the spammer obtained my email address by some means (whether legal or illegal) from Sony. Therefore, I will go into my Sony account, change my email address to something like email@example.com and then go to cPanel and block cqd-sony@
The end result is that I get virtually no spam in that account. I have to say “virtually” because every few months, a piece of spam comes in and I have to follow that procedure. However I can say that I often go many months without receiving a single piece of spam.
To facilitate this, I must be able to set the reply-to an email with the address they sent it to.
At an absolute minimum, there needs to be a “Reply-to” field when composing an email that, if left blank, defaults to the email account or can be over-ridden. Even better would be a macro “” that would substitute the “to” address automatically.
This way, when the person I sent the email to replies back, it comes back where it should instead of to the main address.
(Super duper bonus points would for this configuration item to be in the account settings, including the macro functionality.)
Anyhow, having a Reply-to will allow me to use eM in the manner I described and will allow me to keep my sanity (loosely defined) and life spam-free.
I hope this illustrates another application for the Reply-to function and encourages its addition to the future development path.