If the MTA detects that a message is looping, that message will be sidelined as a .HELD file. See 188.8.131.52 Diagnosing and Cleaning up .HELD Messages. Certain cases can lead to message loops which the MTA can not detect.
The first step is to determine why the messages are looping. You should look at a copy of the problem message file while it is in the MTA queue area, MTA mail log entries (if you have the logging channel keyword enabled in your MTA configuration file for the channels in question) relating to the problem message, and MTA channel debug log files for the channels in question. Determining the From: and To: addresses for the problem message, seeing the Received: header lines, and seeing the message structure (type of encapsulation of the message contents), can all help pinpoint which sort of message loop case you are encountering.
Some of the more common cases include:
The MTA requires that the postmaster address be a functioning address that can receive email. If a message to the postmaster is looping, check that your configuration has a proper postmaster address pointing to an account that can receive messages.
Stripping of Received: header lines is preventing the MTA from detecting the message loop.
Normal detection of message loops is based on Received: header lines. If Received: header lines are being stripped (either explicitly on the MTA system itself, or on another system like a firewall), it can interfere with proper detection of message loops. In these scenarios, check that no undesired stripping of Received: header lines is occurring. Also, check for the underlying reason why the messages are looping. Possible reasons include: a problem in the assignment of system names or a system not configured to recognize a variant of its own name, a DNS problem, a lack of authoritative addressing information on the system in question, or a user address forwarding error.
Incorrect handling of notification messages by other messaging systems are generating reencapsulated messages in response to notification messages.
Internet standards require that notification messages (reports of messages being delivered, or messages bouncing) have an empty envelope From: address to prevent message loops. However, some messaging systems do not correctly handle such notification messages. When forwarding or bouncing notification messages, these messaging systems may insert a new envelope From: address. This can then lead to message loops. The solution is to fix the messaging system that is incorrectly handling the notification messages.
If the MTA detects a serious problem having to do with delivery of a message, the message is stored in a file with the suffix .HELD in /msg-svr-base/data/queue/channel. For example:
% ls ZZ0HXZ00G0EBRBCP.HELD ZZ0HY200C0O6LGHU.HELD ZZ0HYA006LP66O3H.HELD ZZ0HZ7003EOQSE37.HELD
.HELD files can occur due to three major reasons:
Looping messages. The MTA detected that the messages were looping via build-up of one or another sort of Received: header lines).
User or domain status set to hold. These are messages that are, by intent of the MTA administrator, intentionally being side-lined, typically while some maintenance procedure is being performed, (for example, while moving user mailboxes).
Suspicious messages. Messages that met some suspicion thresh hold and were held for later manual inspection by the MTA administrator. Messages can be .HELD due to exceeding a configured maximum number of envelope recipients (see the holdlimit channel keyword in 12.5.9 Expansion of Multiple Addresses), due to running the imsimta qclean in Sun Java System Messaging Server 6.3 Administration Reference, clean in Sun Java System Messaging Server 6.3 Administration Reference or hold in Sun Java System Messaging Server 6.3 Administration Reference commands based on some suspicion of the message(s) in question, or due to use of a hold action in a Sieve script.
Messages bouncing between servers or channels are said to be looping. Typically, a message loop occurs because each server or channel thinks the other is responsible for delivery of the message. Looping messages usually have a great many *Received: header lines. The Received: header lines will illustrate the exact path of the message loop. Look carefully at the host names and any recipient address information (for example, for recipientclauses or (ORCPT recipient)comments) appearing in such header lines. One cause of such message loops is user error.
For example, an end user may set an option to forward messages on two separate mail hosts to one another. On his sesta.com account, the end-user enables mail forwarding to his varrius.com account. And, forgetting that he has enabled this setting, he sets mail forwarding on his varrius.com account to his sesta.com account.
A loop can also occur with a faulty MTA configuration. For example, MTA Host X thinks that messages for mail.sesta.com go to Host Y. However, Host Y thinks that Host X should handle messages for mail.sesta.com; as a result, Host Y returns the mail to Host X.
In these cases, the message is ignored by the MTA and no further delivery is attempted. When such a problem occurs, look at the header lines in the message to determine which server or channel is bouncing the message. Fix the entry as needed.
Another common cause of message loops is the MTA receiving a message that was addressed to the MTA host using a network name that the MTA does not recognize (has not been configured to recognize) as one of its own names. The solution is to add the additional name to the list of names that your MTA recognizes as its own. Note that the MTA's thresh holds for determining that a message is looping are configurable; see the MAX_*RECEIVED_LINES option.dat options (Option File Format and Available Options in Sun Java System Messaging Server 6.3 Administration Reference). Also note that the MTA may optionally be configured--see the HELD_SNDOPR global MTA option--to generate a syslog notice whenever a message is forced into .HELD state due to exceeding such a thresh hold. If syslog messages of Received count exceeded; message held.are present, then you know that this is occurring.
You can resend the .HELD message by running release in Sun Java System Messaging Server 6.3 Administration Reference or following these steps:
Rename the .HELD extension to any 2 digit number other than 00. For example, .HELD to .06.
Before renaming the .HELD file, be sure that the message has stopped looping.
Run imsimta cache -sync. Running this command will update the cache.
Run imsimta submit channel or imsimta run channel.
It may be necessary to perform these steps multiple times, since the message may again be marked as .HELD, because the Received: header lines accumulate. If the problem still exists, the *.HELD file will be recreated under the same channel with as before. If the problem has been addressed, the messages will be dequeued and delivered.
If you determine that the messages can simply be deleted with no attempt to deliver them, see clean in Sun Java System Messaging Server 6.3 Administration Reference in the Sun Java System Messaging Server 6.3 Administration Reference.
Messages .HELD due to a user or domain status of hold--and only messages .HELD for such a reason--will normally be stored in the hold channel's queue area. That is, .HELD message files in the hold channel's queue area can be assumed to be .HELD due to user or domain status.
Messages .HELD due to some suspicious characteristic will of course exhibit that characteristic. The characteristic could be anything which the site has chosen to characterize as suspicious. MTA Administrators should stay aware of these configuration choices and actions. However, if you are not the only or original administrator of this MTA, then check the MTA configuration for any configured use of the holdlimit channel keyword (12.5.9 Expansion of Multiple Addresses), any use of the $H flag in address-based *_ACCESS mapping tables in the MTA mappings file, or any use of the hold action in any system Sieve file (the system level imta.filter file, or any channel level Sieve filters configured and named via use of sourcefilter or destinationfilter channel keywords; see 12.12.4 Specifying Mailbox Filter File Location); and ask any fellow MTA administrators about any manual command line message holds (through, for instance, an imsimta qm clean command) they might have recently performed. Note also that application of a Sieve filter hold action, whether from a system Sieve filter or from users' personal Sieve filters, may optionally be logged; see the LOG_FILTER global MTA option (Option File Format and Available Options in Sun Java System Messaging Server 6.3 Administration Reference) for more information.