I understand some viruses will be imbedded in a winmail.dat file. Unfortunately for us, some of out clients are sending us emails with important information within those files that are attached. But those attachments are being removed. I assume Avast is what is doing this. Is there a setting somewhere to allow those files to come through? We are using Avast Pro. Thanks.

turn off mail shield …

i suggest you upload and test those attachments at one of these places before you open and run them …
avast may be correct in its detection :wink: lots of malware come with mail, or the attachment come from a infected machine
www.virustotal.com / www.metascan-online.com / www.jotti.org

which mail client do you use ?
some programs like MS Outlook block some file types by default. For Outlook I use the freeware add-on attachment options