Two improvements to help with managing rejected emails when Mailgun is your outgoing email provider:

  • When an outgoing email is rejected, Mailgun now notifies Cameo. Cameo then:
    • posts a reminder message about such problems daily (as a batch if there is more than one): subscribe to #EmailBounce to receive these.
    • marks the message in Outbox (in Library) and History (in Membership Info) when it either delivers (green thumbs-up) or gives up trying (red thumbs-down): see Fig 1.
  • If you receive a bounce message from a recipient, this can now be forwarded to Cameo (similar to emailing attachments – detail below). On receipt, Cameo:
    • examines the email looking for the email address which has a problem,
    • marks the most recent email message sent to that address as failed, and
    • notifies Mailgun not to send to that address again until further notice (just as if it had detected the bounce itself).
Fig 1:
A red thumbs-down indicates the message could not be delivered in both Out Box and History. Hover over the icon for the reason given by the intended recipient’s email (or open the email in preview).
A green thumbs-up means the intended email system accepted the message. However, it may still be bounced in an email reply; forwarding such emails deals with this as if it had failed initially.
No delivery status means the message is either still trying, Cameo hasn’t caught up yet (it checks daily in the early hours), your system doesn’t use Mailgun for message delivery, or the message pre-dates this new feature.

Previously, an immediate rejection (while Mailgun is actually connected to the recipient’s email server) caused by an incorrect email address would have been notified. However, messages re-tried several times, but eventually given up, would not have been. They now are (with messages tagged #EmailedBounce, which you can subscribe to to get them by email), and the messages are also marked as illustrated above.

Many email systems directly accept a message and only later reject it with a return email, and for a variety of reasons. If bounces ends up at Mailgun (which they can be set up to be), then it would be dealt with in the same way as direct rejections. But if these bounces only appear in the sender inbox (when Mailgun is not set up to process inbound messages), manually forwarding these to Cameo can achieve a similar result. Send them to your usual inbound email address with +b, +bounce or +bounces added to the subject line, or append that to the email address (as in (Reminder: if you have enabled this, you can see the addresses to send email to Cameo in the Incoming Email section in Organisation Settings).

Why only Mailgun?

This only applies if Cameo originally sent the email via Mailgun. That is because Mailgun arranges for the address to which the message is bounced to contain details about the intended recipient and the email, with a complicated bit before the at-sign, like this:


We look for this pattern in the forwarded message. So if the message was sent, say, to from, then Mailgun will arrange for bounces to come back to something like:

Of course delivery of an email only increases confidence that it has been received. It could still end up in someone’s personal spam folder, or a promotions folder which they rarely look at. Even if it reaches the in -box, it may not be opened or read.

It may be possible to extend this to emails sent via SMTP in future, though this will partly depend on the capabilities of the provider.