Normally the program called by the policy will be visible. There are workarounds to make it run hidden as outlined here:
http://kbase.pmail.gen.nz/viewfull.cfm?ObjectID=4A49C60D-14D8-4FC3-AD5F7E6F739E3B6C 

 /Rolf
 

I get mail from a support BBS that often mangles "Subject:" headers.  They can wind up looking like this.

    RE: [forum-id] Re: subject

That screws up threading in Agent where I ultimately read them (and it's just plain unsightly).  SED.EXE can easily change that to

    Re: [forum-id] subject

Can I use a Mercury filter with action "Run a program" to edit the actual email?  If not, are there any other suggestions?  Thanks.

 - Vince
 

There are two options, policy or daemon, if you want to modify the contents of the message. In this case a policy could perhaps solve it. You'll find policy settings under Core configuration. You need to check "This task modifies the raw data of the jobs it examines" to get it to work. From Mercury help:

 In some cases, you may wish to allow the external task to modify the actual data in the mail message it examines (for instance, you may want it to add a header to the message). Checking this control tells Mercury to copy the temporary file it creates containing the message's data back into the queue job when policy processing is complete. It is your responsibility to ensure that the policy does not corrupt or damage the message data in this case, and to ensure that the message data remains in legal RFC2822 format. Checking this control will slightly increase the time it takes to process policies on your system.

/Rolf
 

[quote user="Rolf Lindby"]

There are two options, policy or daemon, if you want to modify the contents of the message. In this case a policy could perhaps solve it. You'll find policy settings under Core configuration. You need to check "This task modifies the raw data of the jobs it examines" to get it to work. From Mercury help:

 In some cases, you may wish to allow the external task to modify the actual data in the mail message it examines (for instance, you may want it to add a header to the message). Checking this control tells Mercury to copy the temporary file it creates containing the message's data back into the queue job when policy processing is complete. It is your responsibility to ensure that the policy does not corrupt or damage the message data in this case, and to ensure that the message data remains in legal RFC2822 format. Checking this control will slightly increase the time it takes to process policies on your system.

/Rolf

[/quote]

Thanks.  Do/can policy tasks run hidden?