Hi your all, I have used Thurderbird more than 6 years and it was really good for me without any complaints. However, I updated the email from Supernova to Nebular (128.2.3esr (64-bit) yesterday and I got the following message and I cannot receive any emails now. Fortunately, sending is no problem. "Sending of username did not succeed. Mail server pop3.mailplug.co.kr responded: invalid command" I searched the previous similar issues in the forum and I checked my status. However my own was the right one that people recommend. Receiving Server: pop3.mailplug.co.kr / Port: 995 / SSL/TLS / Normal password Sending Server: smtp.mailplug.co.kr / Port: 465 / SSL/TLS / Normal password Actually, I am using several pop email apps but I have no any issues on those apps except for the Thunderbird. The problem is Thunderbird is my main app. I am alternatively using outlook but really want to return to Thunderbird. Could you anyone help me out? Thank you for your kindness in advance!