In Aqua Mail's settings go to the Debug section and enable “Debug logging” there. Set “Log output location” to “File (log-AquaMail.txt)”. You will need to enable “Log raw data (include raw session data)” most of the time, if the issue is related to specific message(s) or account(s). It is good practice to reset the log file from the last option in the menu before proceeding further.

Once logging is enabled, please repeat the steps to cause the issue and send the log file to with a brief description of your problem.

The log file is called log-AquaMail.txt and is located at the root directory of your device. Note that you will have to manually disable the logging process after you've finished.