When you send an email in Intercom, some recipients might not receive the message. These are called dropped recipients.
How to identify dropped recipients
In the conversation stream, you can identify these recipients in the email metadata (the To, Cc, and Bcc fields) by looking for:
A red warning icon next to their name or email address.
Red text to distinguish them from successfully delivered recipients.
To understand why a specific person was dropped, hover over the recipient to see a tooltip explaining the reason.
Drop reasons and what to do
Each dropped recipient includes a specific reason for the delivery failure. Here's what each reason means and how to fix it:
Mailbox is full (user_suppressed)
What it means: Previous attempts to email this address returned a "mailbox full" error. Intercom temporarily suppresses sending to this address to protect your sender reputation.
What you can do: If you believe the address should be reachable again, contact Intercom support to have the suppression reviewed and removed.
Test address (email_address_ignored)
What it means: The email address has been identified as a test address and is being ignored by Intercom's delivery system.
What you can do: If this is a real address that was incorrectly flagged, contact Intercom support. If it is a test address, no action is needed as this is expected behavior.
Bounce list (user_bounced)
What it means: Previous emails to this address have bounced (failed to deliver), so it was added to the bounce list. Continuing to send to bounced addresses can harm your sender reputation.
What you can do: Verify the email address is correct and active. If the address is valid, contact Intercom support to have it removed from the bounce list. Otherwise, update the contact's profile with a valid address.
Communication preferences (user_not_contactable)
What it means: The recipient has unsubscribed or opted out of communications.
What you can do: Intercom cannot bypass these preferences. If you must reach them, try an alternative channel like chat or phone.
Blocked domain (banned_domain)
What it means: The recipient's entire email domain has been blocked, preventing all addresses on that domain from receiving messages.
What you can do: If you believe the domain was blocked in error, contact Intercom support for a review.
Other reasons
What it means: In rare cases, a generic "This address can't be emailed" message may appear for reasons not listed above.
What you can do: Check the contact's profile for flags. Contact Intercom support if you believe they should be able to receive emails.
FAQs
Does the sender see dropped recipients?
Yes, dropped recipients are visible in the email metadata for both collapsed and expanded views. They appear alongside successfully delivered recipients so you can easily see who did not receive the message.
Are dropped recipients removed from the conversation?
No, they remain listed in the email headers. They are visually marked to show delivery wasn't attempted, but they stay in the recipient list.
Can I retry sending to a dropped recipient?
Not directly from the conversation. You must resolve the underlying issue first (such as contacting support to clear a bounce list status) and then send a new message.
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