This is a new app which uses MAPI to add an email to address, a subject some text t the body and a pdf attachment. When I put the app together I tested it on Thunderbird ver 38.5.0 and it worked great. The MAPI controls added the info to a T'Bird email and then displayed it for verification and or additions. When I clicked send it successfully sent the email with the attachment. I then updated to ver 52.something and the problem started. The attachment is: path = "c:\program files\PritShopManager\Export\" the files name is "Qt-010004.pdf". When I click send I get a error: Unable to open the tempory file c:\Users\User\AppDate\Local\Temp\moz_mapi\Qt-010004.pdf. Check your 'Temporary Directory' setting. When I got to c:\Users\User\AppDate\Local\Temp\moz_mapi\Qt-010004.pdf, Qt-010004.pdf is not a file but it's a directory. The Qt-010004.pdf directory is empty. After trying several times, I get directories Qt-010004.pdf, Qt-010004-1.pdf, Qt-010004-2.pdf, Qt-010004-3.pdf, Qt-010004-4.pdf, etc. The MAPI connection worked before the update but not after.