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

Question

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      joe bloggs a com --  notifications b com --  peter c com   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  notifications b com   A simple solution may be to change the Reply-To header on the notifications we send to the relevant Company A address e g      joe bloggs a com --  notifications b com  Reply-To  joe bloggs a com  --  peter c com   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

User · Accepted Answer

You may want to consider placing the customer's name in the From header and your address in the Sender header:

From: Company A <[email protected]>
Sender: [email protected]

Most mailers will render this as "From [email protected] on behalf of Company A", which is accurate. And then a Reply-To of Company A's address won't seem out of sorts.

From RFC 5322:

The "From:" field specifies the author(s) of the message, that is, the mailbox(es) of the person(s) or system(s) responsible for the writing of the message. The "Sender:" field specifies the mailbox of the agent responsible for the actual transmission of the message. For example, if a secretary were to send a message for another person, the mailbox of the secretary would appear in the "Sender:" field and the mailbox of the actual author would appear in the "From:" field.

User · Answer

After reading all of this  I might just embed a hyperlink in the email body like this  To reply to this email  click here  lt a href  quot mailto     quot  gt Third Party theirdomain com lt  a gt

User · Answer

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  messages-noreply bounce linkedin com From  John Doe via LinkedIn  lt member linkedin com gt  Reply-To  John Doe  lt John Doe gmail com gt  To  My Name  lt My Name gmail com gt    Once I switched to this format  gmail is no longer filtering my messages as spam

User · Answer

Here is worked for me   Subject  SomeSubject From Company B  me  Reply-to Company A To Company A s customers

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

Examples related to email

Examples related to spam

Examples related to email-headers

Examples related to phishing