Which service sent it
The service behind the sender.
Beside the sender, a mark names the service a message was sent with, from Gmail and Outlook to SendGrid and Mailchimp. Mail that reached you through a forward says so too.
In short
How can you tell which service sent an email?
A sending service leaves traces in the headers of what it sends: the key it signs with, headers of its own, the domain in the Message-ID or the name of its mail program. OpenEmail reads them as a message arrives and names the service beside the sender.
How it works
Read from the headers, in order
As a message arrives, the signing key is read first, then the service’s own headers, the domain in the Message-ID and the mail program it names.
Forwards say so
Mail that reached you through a forward gets a Forwarded badge by the To line and a note naming the address it was forwarded from. Mail addressed to someone else, such as a copy passed on to you, says Sent to that address instead.
In the API as sentWith
The REST API and the SDK return the service as sentWith and the forward as forwardedFrom on every message. The MCP server includes both when it reads a conversation.
What you get
In the product today
Listed in Details
Details lists the service too, as Sent with.
Your own mail
Your own mail carries the OpenEmail mark, as does mail from any domain that sends through OpenEmail.
Replies come from you
Replies always go out from one of your own addresses, forwarded mail included.
Good practice
Getting the most out of it
- 01
Read it with the sender checks
The mark names the service, and the sender checks under Details show whether the message came from the domain it claims.
- 02
Read the forward note
It names the address the mail was forwarded from, and your reply goes out from one of your own addresses.
- 03
Sort by sentWith in your own tools
The REST API and the SDK return sentWith on every message, so a script can tell mail sent with Mailchimp from mail sent with Gmail.
Questions
Asked often
Keep going
Works well with
Start
Your domain,
your mail.
Point a domain at OpenEmail and read it in a mailbox built around it. The free plan covers one domain.