I have a client that has three laptops running Windows 11 and the latest build of Thunderbird. She has the same three email addresses (MSN.com, outlook.com and gmail.com) added to TB on all three computers. When sending a test message to one of the email addresses they arrive in the inbox on just two of the computers and not on the third one. All three email accounts have identical POP/SMTP settings and "Leave mail on server" is checked. Any ideas as to why just one of the computers would not receive inbound email messages? When I added the account to the computer in question, there were no error messages, and the account addition was successful. Any thoughts as to what might cause this?