Operating System - OpenVMS

Mailbox Problem.

Occasional Contributor

Mailbox Problem.

Hello every one....


For some time I am facing a problem in my Open VMS system related to mailbox.

While executing Boxfull command it says the following.


Mailbox- ALARM_PROC_EMS (MBA1730) has 26 entries.

Mailbox - RU$ALARM_EMS (MBA1732) has 1 entries.

No group mailbox found for number MBA5786

Mailbox- (MBA5786) has 1 entries.


I am having Open VMS version 7.2-1 installed in Alpha DS10 machine.


There are several customised applications running in the system and ALARM is one of them.The Process is controlled by another process called PROC. These processes communicates via mailbox with eachother and also with other applications running.


At present I am not able to find out the reason behind the above messages where there are several entries agains mailboxes as shown above.


I neet to troubleshoot this issue.Can somebody help me out with the commands and all to troubleshoot the issue?


I am not that much conversant with the fundamentals of mailbox too.




Respected Contributor

Re: Mailbox Problem.

This is an application issue that will require knowing how the application expects to work. You are not likely to completely address the problem here. I would suggest that you seek assistance from someone with OpenVMS experience. On-site assitance would be your best option.

To get some generic debugging info from here, please update this posting with some info about Boxfull. What exactly is this? Is this a product or an inhouse application?

John Gillings
Honored Contributor

Re: Mailbox Problem.



   A mailbox is a memory buffer into which messages can be written or read by any process with appropriate security access.  Usually there's a single reader process servicing a mailbox, with one or more writers. In some application designs, communication is bi-directional, with a mailbox for each direction.


  In most cases the reader will remove messages from the mailbox as quickly as possible, so there should be little or no accumulation.  In your case ALARM_PROC_EMS has 26 entries, which suggests that whatever process is supposed to be reading the message has either terminated, or is stuck. RU$ALARM_EMS also has an entry, so its reader process may also be stuck. Since they're so close in unit number, and have similar names, it's likely they're related (possibly a bi-directional pair).


"Boxfull" is not a normal VMS command. I'd guess it's a utility local to your system. 


Look at a SHOW SYSTEM display for this system. See if there are any processes in RWMBX state - that indicates that they're attempting to write a message to a full mailbox.


See if you can work out which processes are supposed to be reading your mailboxes, and what state they're in. Perhaps you can restart them?


If the messages aren't critical, you can always clear the mailbox with




This will dump the messages to the terminal as text. Hit ^Y when the output stops. BEWARE this means you've thrown away the messages. This may be useful to get your system unstuck, but if someone needs to see whatever the alarms are, it might not be such a good idea.


Talk to whoever supports the application, or engage a consultant to work out what's going wrong. It's possible the design has a timing problem where it can get itself into a deadlock.

A crucible of informative mistakes
Occasional Contributor

Re: Mailbox Problem.

Thanks John.This is really a helping post that helps me to atleast understand about the basics of mailbox.


I have searched in the system with SHOW SYSTEM  command and found that there is one process that is in RWMBX state. And  atlast I had to do a restart of the system since the process was not properly getting killed.