Problem with broken attachments in Zimbra

Question

Email

Hello!
Tell me where to dig: we send files from one Zimbra server to another - messages arrive broken, mostly office documents - xlsx, docx, tif. But not always, but once in a while. Zimbra version on both servers is 8.0.5_GA_5839.FOSS. Clients - Outlook Express.

Answer 1

The problem was in the built-in antivirus. Apparently, the imposition of several factors (different cryptorouters, encrypted traffic) caused this problem. After disabling the antivirus, the files stopped beating.