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Outlook 2010 & 2013 Chaning attachment names

We have a situation where outlook seems to be changing all attachment (sent and received) so that when you attempt to open them, the Windows OS can't open the file.
For example.
Create an email, attached a quote as a quote.pdf....when outlook attaches and send the file, it's now renamed to quote.pd_
There are no macro's in place, this update is slowly creeping it's way through my work pc's (it was only 1 machine 2 weeks ago, we now have over 10 with the same problems).

Has one else seen this ?
Watch Question

what anti-virus , anti-spam you are using
can you check if this has to do on client version update of those software,
JohnBusiness Consultant (Owner)
Most Valuable Expert 2012
Expert of the Year 2018

That has never happened to me in any version of Outlook.

I would start doing Full virus scans with your own A/V application AND with Malwarebytes.

Are you able to open the attachments?  Beware of the cryptolock virus.


We are using Kaperski.....the weird thing is, we've been using this for over a year and it's only started to creep in.

(It also changes jpeg's, doc, Excel's everything (jpe_; do_; xls_;)
it is kaspersky
check this url from product support


Spot on, you can alter the files it changes.