Hello there Kinates Not receiving mail on a thin client? Check the antivirus software and the thin client's firewall. Try using troubleshooting mode to check add-ons and extensions. Try to make exceptions in these security settings and software '''''Looking at the facts''''' System Time: Ensure the thin client’s clock and time zone are accurate. Even a few minutes of 'drift' can cause security certificate errors. Firewall Rules: Verify the system firewall isn't blocking Thunderbird's connection. Security Exceptions: If the mail syncs correctly in ''Troubleshooting Mode'', it’s likely your Antivirus or a local security suite. Try adding a specific exception for the Thunderbird executable in those programs." Making exceptions at the software security for thunderbird after disabling that. If the security software is the culprit '''''Update security protocols''''' Updating security protocols , the thin client is sensitive '''''Use''''' https://support.mozilla.org/en-US/kb/troubleshoot-mode-thunderbird https://support.mozilla.org/en-US/kb/cannot-receive-messages '''''Linux''''' Check RAM: Run ''top'' or htop to see if a ''runaway'' process is eating the memory.