ME020514 - HOWTO: MTA crashing and messages not being delivered. Messages building up in SMTP or Post Office Queues.


SUMMARY

The details below are designed to give directions in the event that the MTA service is crashing.  The MTA service is quite simple in it's actions and generally does not change.  With this the case the crashing of the service more likely to be due to a remote service plug-in or a new incorrectly formatted message that it has not encountered before.

DETAIL

MailEnable takes the crashing of any service seriously and as such you should in the instance of a crashing service submit a support request via the MailEnable web site to ensure that it is known and can be resolved as quickly as possible.  Prior to doing so it is always recommended that you ensure that you are running the latest version of the product type that you have installed.  You can download and install the latest version of MailEnable by clicking here.

The MTA service picks up messages from the MailEnable queues and distributes them around the MailEnable server queue sub system.  When the MTA crashes it may not be immediately noticeable as all the messages from any client will appear to be working as normal.  The problem however is that the messages while accepted by the other services will not be getting processed and making it to their destination.  When the MTA service crashes however it does mean that no messages are lost as the messages will be delivered when the MTA is up and running again.  To find out if a service within MailEnable is crashing you can check the service manager in the ME Admin MMC at the following location;

ME Admin MMC->Servers->Localhost->System->Services

Note: If a service in this view is red then it is stopped if the service is green then it is up and running correctly.  if you right click and start a service that is red and it immediately goes to red after you refresh the screen (F5) then the service is crashing on a message for a reason that is most likely covered below.

The MTA service generally does not crash on its own and in nearly all cases the service crashing will be due to a plug-in or service extension such as filtering or anti virus.  With this being the case the best way forward to find out what is causing the crash if the logs do not help is to start disabling the add-ons that you may have enabled.  By disabling each feature as you go and then turning on the MTA service you can quite quickly work out which add-on is causing the crash and then from here work out why.

Here is a list of features that you can disable before restarting the MTA service each time. If the MTA service stops crashing after one of these features is disabled it lets you know what is the cause and you should at this time let MailEnable support know and send through any relevant log files.  If the MTA was stopping because of a plug-in processing a particular type of message then you can sometimes restart the add-on and not see the problem again.  If the service does crash again however, then you should again pursue the support ticket that you created via the MailEnable support page.  For a faster result on this then you can try the steps below as they allow you to find out more about the reason.

Here is a list and location of the features that can be disabled for this diagnoses;

MTA Pick up Event:

ME Admin MMC->Servers->Localhost->Agents->MTA Properties->General TAB->"Enable Pick Up Event"

(Remove tick from this box) then restart the MTA to see if it helps.

MailEnable Filtering:

ME Admin MMC->Servers->Localhost->Filters Properties->General TAB

(Remove tick from "Enable the processing of system filters for this server" box) then restart the MTA to see if it helps.

Anti Virus:

ME Admin MMC->Servers->Localhost->Filters->MailEnable Message Filter->(Right Panel) MailEnable Antivirus Filter Properties->Disable all AV plug-in's.

Take a note of what you have disabled here if required so you know which to enable again when required.  Restart the MTA service and see if it crashes again.

Bayesian Auto Training:

ME Admin MMC->Servers->Localhost->Filters->MailEnable Message Filter->(Right Panel) MailEnable Bayesian Filter Properties->Auto-training TAB

(Remove tick from the "Enable auto-training" box) then restart the MTA to see if it helps.

Spam Protection:

ME Admin MMC->Messaging Manager->Spam Protection Properties->Spam Protection TAB

(Remove tick from the "Enable spam protection" box) then restart the MTA to see if it helps.

If after the process above your MTA service is still crashing then the following steps may help as this will mean that a particular message in the inbound queues is causing the service to stop.

Check the SMTP service queue:

  • Stop all services
  • Make a folder on your desktop named SMTP-inbound and move all the *.MAI message files from the following default location to this desktop folder;

\Program Files\Mail Enable\Queues\SMTP\Inbound

NOTE: This step will mean that all the messages that were currently in the queues will not be processed and all new inbound SMTP messages will be processed instead.  At a later date after we verify if this move has worked we will move the messages back into the queues for processing.

  • It is a good idea to change the MTA service thread count to be one as this will help you narrow down which singular message is crashing or getting stuck by the MTA process.  You can change this feature to 1 at the following location;

ME Admin MMC->Servers->Localhost->Agents->MTA Properties->General TAB->"Maximum Threads"=1

  • Restart all services

At this time if the MTA service stops crashing then you know that a message from the SMTP inbound queue was crashing the service and you can then follow the steps below to try and find the actual message.  If the service keeps crashing then you can move the messages back into the queue folder from the desktop "SMTP-Inbound" folder and then go to the next heading in this article "Check the Post Office service queue:" as we will need to complete these same steps for the Post Office Connector Queue.

If the crashing did stop after the SMTP queue move previously completed, then to try and find the actual message the process is to start copying the messages from the desktop folder SMTP-inbound back into the \Program Files\Mail Enable\Queues\SMTP\Inbound folder.  It is a good idea to copy the messages back into the folder at a rate of about 10 per time and then watch the queue until either the messages are gone or the MTA service crashes again.  If you have a large amount of messages then you may like to try and narrow this down by using larger quantities of the message files.

Check the Post Office service queue:

  • Stop all services
  • Make a folder on your desktop named POC-inbound and move all the *.MAI message files from the following default location to this folder;

\Program Files\Mail Enable\Queues\SF\Inbound

NOTE: This step will mean that all the messages that were currently in the post office queues will not be processed and all new messages in the queue will be instead.  We will put the messages back in later for them to be reprocessed.  Usually the messages in this queue are there from the web mail clients sending.

  • It is a good idea to change the MTA service thread count to be one as this will help you narrow down which singular message is crashing or getting stuck by the MTA process.  You can change this feature to 1 at the following location;

ME Admin MMC->Servers->Localhost->Agents->MTA Properties->General TAB->"Maximum Threads"=1

  • Restart all services

At this time if the MTA service stops crashing then you know that a message from the Post Office Connector inbound queue was crashing the service and you can then follow the following steps to try and find the actual message.  If the service keeps crashing at this stage then you will need to wait until a MailEnable technician looks into it further for you but this is unlikely if the previous steps are correctly followed in this article.

To try and find the actual message the process is to start copying the messages from the desktop folder POC-inbound back into the \Program Files\Mail Enable\Queues\SF\Inbound folder.  It is a good idea to copy the messages back into the folder at a rate of about 10 per time and then watch the queue folder until either the messages are gone or the MTA service crashes again.  If you have a large amount of messages then you may like to try and narrow this down by using larger quantities of the message files.

MORE INFORMATION

Possible error in the MTA logs for crash

Article ME020260

Crashing services

Article ME020058

Messages not process be MTA

Article ME020497

REFERENCES

MailEnable Support Form Click Here

 



Product:MailEnable (All Versions)
Module:MTA
Keywords:MTA crash queues messages build up SMTP
Class:HOWTO: Product Instructions
Revised:Sunday, May 15, 2016
Author:
Publisher:MailEnable