Our business has "contact" forms where web users can send messages to our clients. A web user who wants to send a message to our client will fill out a form and include his email address in the form. Typically these messages are sent to our clients from a do-not-reply email address and inside the email we put the email address of the web user contacting them. When one of our clients gets an email it starts off like this:
DO NOT REPLY TO THIS MESSAGE, it will not go to the person writing you. Instead, copy and paste the following email address: firstname.lastname@example.org
It is hard for our clients to 'respond' using cell phones since they have to change the TO field, rather than just replying. Ideally, I'd like to have our server send out the email but say that it is "FROM" the webuser so that our clients can simply click 'reply'. My fear is, however, that if we do this, we will get "filtered" by all kinds of ISP's since the "FROM" field doesn't match the server sending the email.
Is my fear legitimate? Do many ISP's filter or flag email where a "FROM" field does not match the origination server?