Sometimes, messages will be shown on a recipient’s email system—notably on mobile devices—with the “Reply-To” address displayed, even if only the “From” address was expected.
This is a design choice by the mail application's creators, not an error within Mapp Engage. Mapp Engage cannot influence this.
Technical Explanation
An email is made up of multiple parts. At its simplest, it consists of a header containing technical details about how the message was sent, sender and recipient address details, the subject line, information about the servers the message passed through between the sender and the recipient, and a body containing the actual message.
Within the email header specifications, there are two obligatory fields, “From” and “To,” which define who sent the message and who it was sent to. There’s one optional field, “Reply-To,” which allows you to specify that any replies to a message need to be sent to a different address than the original sender defined in “From.”
How this works in Engage
When Engage sends a message, a group must be selected. This allows the message to use the From, To, and Reply-To addresses set in that group.
Reply-To:
The Reply-To (and the default From address) is adapted from the group’s own name and corresponding email address. Every message sent using this group will use these details. The Reply-To allows responses and bounces to be collected by Engage and, in a standards-compliant way, ensures that any replies are categorized against the correct group for statistics and reply handling processing.
You can change the group name, but you cannot change the underlying group email address, and no two groups can share the same group email address. If you need a new email address for any reason for a group, you need to create a new group.
From:
The From address indicates who sent the email. By default, this will be the name and the email address of the group used for the message sent, but this can be changed. You are free to set the local part (to the left of the @ in the email address), but you can only select authorized domains to ensure that your email is correctly identified as legitimately sent from your system to ensure deliverability quality.
There are other settings options, which are explained in more detail here: Reply Handling (tab)
To:
By default this will be the name and email address of the recipient. This can be changed, but we don’t recommend changing the default value. More details on this can be found here: Reply Handling (tab)
Upon reception
When a message is received and displayed on a recipient’s mail client, you may only expect to see two addresses: From and To. But, this depends on your email system.
For example, as of 2025 both Microsoft Outlook desktop and mobile will by default only display these two fields, but Apple Mail on iPhone will actually display From, To, and Reply-To on separate lines.
As Mapp Engage requires all of these fields to ensure email compatibility, we cannot remove any of these values. How these header values are displayed is purely up to the recipient’s mail system and cannot be influenced by Mapp.
Recommendation
All addresses are present in the header and so can potentially be seen by a recipient, and all 3 addresses are required for an email to be sent.
As there is no way for Mapp to know how a mail system will display the header information, you must take special care in selecting names for your groups, and where possible, use the name and email address of the group as the default reply address. You can reuse the same name across groups - only the underlying email address must be unique!
Document Technical Reference: h9qu4