Hi there, I have been having problems with Thunderbird for a few days now on a new laptop. I have tried uninstalling and reinstalling. I think it maybe a problem with BTinternet but webmail is working fine. I am completely unable to send messages, but can receive them fine. I'm using IMAP and all settings are correct. I have checked and triple checked all port and SMPT settings. Tried running in safe mode, tried disabling antivirus (kaspersky) and my firewall. Nothing makes any difference. I'm not very computer savvy, but have read through every post on this issue and tried every step recommended and nothing has worked. Oddly I was unable to send messages all day Sunday and then suddenly I could again. Then yesterday I was unable to send and I still cannot send. Close to giving up on Thunderbird even though it's the only email client I like. It was showing another error message whilst loading older emails when I first installed it. But I ignored the error as it was receiving and sending fine at the time! I suspect it's a BT issue, but could it be incompatible with Kaspersky? I don't know if anything has updated, all I've done is uninstall and reinstall Thunderbird and disabled every possible related setting in Kaspersky. Thanks for your help, I'm attempting to attach a screenshot of the error message I get once it's been hanging for a while and I've clicked cancel. Jen