Since a couple of days I have a problem with Thunderbird. I can send normal emails without attachments and I have no problem, but when I attach, it keeps loading in 12%, as if it was checking the files, and from there it doesn't go beyond that until it gives a timeout error. I have tried with another email client and it has worked without problem from the same computer. I have paused the antivirus protection in case that was the problem, but it hasn't been the case.