Strange Outlook behavior

[groston]

My system: Windows 7 running Outlook 2010 (version 14.0.4760.100, 32 bit). The default program for opening both .zip and .gz files is 7-Zip File Manager.

I receive a few DMARC reports daily. The ones from google come in a zip file, I double click them in the email message, 7 Zip opens them, and I can extract the report without issue. Other reports, such as those from enterprise.protection.outlook.com, come in a gz file, I double click them in the email message, 7 Zip opens them, but the '.' before xml (in the report's file name) is missing. However, if I move the gz file to my desktop, then double click it, the file name is correct.

It has been suggested that this is an Outlook issue - is there some way to fix this really odd behavior???