Bounced Messages

This article describes how administrators can view messages that have been accepted by the Mimecast Gateway but couldn't be delivered to their recipients. These messages are displayed in the Bounced Messages viewer under the Message Center.

Messages are bounced for several reasons. When a bounce occurs, we send a Non-Delivery Report (NDR) to the message's originator informing them that the delivery failed. To troubleshoot failed delivery, you can view information about the message and the reason for the bounce, and use this to address the cause and resend the message.

Bounced messages (both inbound and outbound) are still available in the archive, as the message was originally accepted by Mimecast before being bounced.

Viewing Bounced Messages

You can view Bounced Messages, by using the following steps:

1. Log in to the Mimecast Administration Console.
2. Navigate to Message Center | Bounced Messages.
3. The information displayed is outlined below.

By default, the queue displays all bounces for the day, although bounce information is retained for 30 days.

Column	Description
From (Header)	The sender's Header From email address. This is used by the email client to display information in the From field.
From (Envelope)	The sender's Envelope From email address. This is used by the SMTP server to generate the NDR.
To	The recipient's email address.
Subject	The message's subject.
Date / Time	The date and time the message was sent.
IP Address	Displays the IP address of the server that bounced the message. If a message is expired from the held queue, no IP will be available. This is unlike Message Tracking/Accepted Messages where we display the sending server IP address.
Attachment	Displays whether the message has an attachment or not.
Size	The size of the message in KB.
Route	Displays whether the message was sent inbound or outbound.
Bounce Info	Displays additional information (e.g., a rejection code received by us when attempting delivery or a reason for the delivery expiring in the delivery queue).
Bounce Type	Displays whether the message was a hard or soft bounce: Hard Bounce: The receiving mail server has rejected the connection. Examples of this are an invalid recipient email address or a full mailbox. Soft Bounce: The message could not be delivered within our retry schedule (30 attempts over four days). Examples of this are if the recipient's mail server is temporarily unavailable, or the recipient domain's MX records cannot be located.

4. You can customize the view of the bounced messages page and apply filters to display only the most relevant details. View the Message Center - Customizing Message Views page for further information.

Messages that have been blocked by end users The Digest Email are also logged in bounced messages. These messages are both bounced and the sender's details added to the user's personal block list.

Customizing the Views

You can customize the view of the Bounced Messages page and apply filters to display only the most relevant details. See Message Tracking - Customizing Message Views

Searching for Bounced Messages

To search for specific bounced messages and refine the results:

1. Click on the All drop-down menu.
2. Select from one of the following options:

• From: Searches by the From email header information.
• To: Searches by the To email header information.
• Subject: Searches by the message subject.
• IP Address: Searches by the IP address of the server that bounced the message.

2. Enter any known message details in the Search field.

3. Click on the Search icon.

   

Exporting Search Results

You can export your bounced message search results to a downloadable file. View the Export Results in Accepted Messages page for details.

Mimecast Bounce Information

The most common types of bounces related to Mimecast users are listed below, as displayed under the Bounce Info column. Bounces from remote servers may issue a different reason.

Bounce Type	Description
Expired in Queue - Rejected by Housekeeping	A held item expires and bounced from the held queue after 14 days.
SMTP Code [Error Description]	See the Mimecast SMTP Error Codes  page for a full description.
Rejected by Reviewer or an Administrator	An administrator rejected the message from the hold queue.
Message Bounced - Spam Signature Policy	We accepted the message but bounced it after a Spam Scanning Policy triggered a reject action.
Message Deleted Due to Content Examination Policy	We accepted the message but bounced it after a Content Examination Policy  triggered a delete action.
Message Deleted Due to Impersonation Protect Policy	We accepted the message but bounced it after an Impersonation Protection Policy triggered a delete action.
Recipient Email Address is Possibly Incorrect	The recipient's email address doesn't exist.
Recipient Server Unavailable	The destination server couldn't be contacted, although the IP address was resolved.
Recipient Email Server Rejected the Message	The destination server rejected the message.
Recipient Mailbox is Full	The destination user's mailbox is unable to accept more messages.
Unable to Authenticate During Send	SMTP authentication is configured for a delivery IP address and cannot be verified.
Unable to Deliver Encrypted Message	TLS delivery is enforced, but the remote server doesn't support it.
Unable to Move Email to CCM	A CCM item cannot be added to a CCM mailbox.
Connection Refused	On delivery, our connection to the recipient server was rejected.
Connection Timed Out	We were unable to connect to the delivery IP address.
Domain has no MX Records or is Invalid	The DNS lookup is producing empty MX records. This is normally due to a spelling mistake in the email address's domain.
Expired in Queue - Rejected by User Header Block List	A user rejected the message.
No Route to Host	The next hop mail server couldn't be contacted, despite a successful connection to the IP address.
Read Timed Out	We were waiting for a reply during the SMTP transmission, which wasn't received in a timely fashion.
Temporary Error Looking Up MX record	The DNS or associated MX records for the destination domain couldn't be resolved.
Could Not Progress Past Recipient in Protocol	We established the SMTP communication string and progressed to the MAIL FROM and RCPT TO, but not as far as the DATA command. The destination mail server may be running low on resources (e.g., memory, available disk space).

Reporting Messages

You can report messages on either the bounced messages page or from the message details pop-out panel.

To report a message from the bounced messages listing:

1. Click on the icon in the far right corner of the message.
2. Select to report as Spam, For Support, Malware, or Phishing.

3. Enter your comment/reason into the popup box displayed.
4. Click Report. The message is submitted to Mimecast for analysis.

See Also...

• Message Center - Message Tracking
• Accepted Messages