[email] Should I use the Reply-To header when sending emails as a service to others?

Suppose we have an application that acts as a middleman, allowing Company A to send reports to their customers.

Company A --> Company B (me)--> Company A's customers

After getting the report we send email notifications to the recipients, but they necessarily originate from our company notifications email address e.g.

[email protected] --> [email protected] --> [email protected]

Now, customers tend to reply to those email notifications, wanting them to go back to whoever sent the report at Company A. Instead, they end up back at our address, [email protected].

A simple solution may be to change the Reply-To header on the notifications we send to the relevant Company A address e.g.

[email protected] --> [email protected] [Reply-To: [email protected]] --> [email protected]

But my main concerns are:

• the complete discrepancy in email address and domain between the From and Reply-To fields might make spam or phishing filters more eager to flag the emails
• not all email clients may respect the Reply-To field when people actually click "Reply", and just use From instead. A lesser concern, unless widespread.

Are these concerns founded at all? Or, are there other concerns I should have?

After reading all of this, I might just embed a hyperlink in the email body like this:

To reply to this email, click here <a href="mailto:...">[email protected]</a>

I tested dkarp's solution with gmail and it was filtered to spam. Use the Reply-To header instead (or in addition, although gmail apparently doesn't need it). Here's how linkedin does it:

Sender: [email protected]
From: John Doe via LinkedIn <[email protected]>
Reply-To: John Doe <[email protected]>
To: My Name <[email protected]>

Once I switched to this format, gmail is no longer filtering my messages as spam.

Here is worked for me:

Subject: SomeSubject
From:Company B (me)
Reply-to:Company A
To:Company A's customers