I noticed a new problem which might did come out with gpg4win 3.1.5.
When a SMIME signed email was openend by the receipient, sometimes (not always) the program “GnuPGs X.509/CMS tool (32 Bit)” = gpgsm.exe is started three times. Therefore the SMIME email cannot be opened in Outlook. Closing Outlook and restarting Outlook does not help. Sometimes windows log-off and log-in helps. The problem can be solved by killing gpgsm.exe using Taskmanager or killtask-commandlet. But of course this not a “nice” solution.
Any suggestions? Thanks