Hello there You cannot receive or send. Email. What version of thunderbird do you use? Can you update it to that latest version that is on that pc , is it installed? Could be that antivirus, disable it for a while at least the scans for the program ? Also the look a like programs : mall ware etc. smtp settings are filled in ,right ,do they match with the provider? Check for working online and offline modes in thunderbird’s option's is it turned off? https://www.thunderbird.net/en-US/thunderbird/releases/