avoop server error

Hi, I've two Symantec Messaging Gateway servers; one 10.0.3-3 and one 10.5.1-2 version.

Sometimes the first, sometime the second one but never at the same time, one of them present the following message error:
avoop: a connection to the avoop server could not be established (#13019).

This usually occurs sporadically, maybe twice a month.

I've not detected any problem with the service, but I would like to know what is avoop server, or the meaning of this error. Is it critical?

I found this article, but i doesn't say much about it, http://www.symantec.com/business/support/index?pag...

Thanks!