Email, Messaging, & Video Calls > Email Log POP, IMAP, and SMTP Traffic in Mozilla Thunderbird Check the logs to troubleshoot email errors By Heinz Tschabitscher Heinz Tschabitscher Writer University of Vienna A former freelance contributor who has reviewed hundreds of email programs and services since 1997. lifewire's editorial guidelines Updated on February 11, 2020 Tweet Share Email Hero Images / Getty Images Tweet Share Email Email Yahoo! Mail Gmail Logging POP, IMAP, and SMTP email traffic isn't just for the industrious developer. If you want to see what's going on behind the scenes of your email exchanges in Mozilla Thunderbird (especially if what's going on is not going right), logging yields lots of information that can help you or your tech-support person diagnose the problem. Turning on transaction logging may not be a straightforward affair, but it is not difficult, either. To create a log file with all Post Office Protocol, Simple Mail Transfer Protocol, and Internet Message Access Protocol traffic in Mozilla Thunderbird, first, make sure it's not running. Then, follow the instructions for your operating system. Turning on Transaction Logging in Windows In Microsoft Windows, follow this procedure: Open the Command Prompt. Press Win+X and click Command Prompt to open the Command Prompt. Type set NSPR_LOG_MODULES= followed immediately by: POP3:4 for POP loggingIMAP:4 for IMAP loggingSMTP:4 for SMTP logging Enable logging for multiple protocols by separating them with commas. For example: To log both POP and SMTP traffic, type: set NSPR_LOG_MODULES=POP3:4,SMTP:4 To log only IMAP traffic, type: set NSPR_LOG_MODULES=IMAP:4 Press Enter. Type set NSPR_LOG_FILE=%HOMEDRIVE%%HOMEPATH%\Desktop\tbird_log.txt Press Enter. Type start thunderbird Press Enter again. Perform the desired email actions in Mozilla Thunderbird. Quit Mozilla Thunderbird and open tbird_log.txt on your Desktop. Turning on Transaction Logging in macOS Use the following procedure on your Mac: Open a Terminal window. Type set NSPR_LOG_MODULES= followed immediately by: POP3:4 for POP loggingIMAP:4 for IMAP loggingSMTP:4 for SMTP logging Press Enter. Enable logging for multiple protocols by separating them with commas. For example: To log both POP and SMTP traffic, type: export NSPR_LOG_MODULES=POP3:4,SMTP:4 To log only IMAP traffic, type: export NSPR_LOG_MODULES=IMAP:4 Type export NSPR_LOG_FILE=~/Desktop/tbird.log Press Enter. Type /Applications/Thunderbird.app/Contents/MacOS/thunderbird-bin Press Enter again. Perform the desired email actions in Mozilla Thunderbird. Quit Mozilla Thunderbird and find tbird.log on your Desktop. Turning on Transaction Logging in Linux In Linux, follow this procedure: Open a Terminal window. Type set NSPR_LOG_MODULES= followed immediately by: POP3:4 for POP loggingIMAP:4 for IMAP loggingSMTP:4 for SMTP logging Press Enter. Enable logging for multiple protocols by separating them with commas. For example, type: export NSPR_LOG_MODULES=POP3:4,SMTP:4 to log both POP and SMTP traffic and export NSPR_LOG_MODULES=IMAP:4 to log only IMAP traffic. Type export NSPR_LOG_FILE=~/tbird.log.txt Press Enter. Type thunderbird Press Enter again. Perform the desired email actions in Mozilla Thunderbird. Quit Mozilla Thunderbird and review tbird.log.txt in your Home directory. Turn Logging off in Mozilla Thunderbird Traffic logging is enabled only for the session you start from the command line. You do not have to turn it off. Was this page helpful? Thanks for letting us know! Get the Latest Tech News Delivered Every Day Subscribe Tell us why! Other Not enough details Hard to understand Submit