If DropDMG itself crashes, the DropDMG Crash Reporter window should automatically come up. Make sure that you enter a valid e-mail address and then click the Send Report button.
If your mail program (or a helper process such as hdiutil) crashes, you’ll need to send in the crash log file manually.
Crash logs are stored in the folder:
/Users/<username>/Library/Logs/DiagnosticReports/
First click on the Finder in the Dock, then click on the Go menu, and hold down the Option key as you choose Library. Open the Logs folder, then DiagnosticReports.
Once you’ve opened the DiagnosticReports folder, find the most recent crash log file for the app that crashed and add it to your e-mail message to dropdmg@c-command.com as an attachment.
The crash log file’s name will end with either .crash or .ips. It may be in the DiagnosticReports folder or in the Retired folder inside of DiagnosticReports.