Since 15th May 2025, some of our employees PCs cannot download incoming e-mails. PC conditions (such as security condition, etc) are the same before and after 15th May 2025. E-mails can be downloaded if I delete current account and again add the account. However, in some of PCs, some certain e-mails can not be downloard although most of the e-mail can be downloaded. I do not find any problem in e-mail server itself. I doubt an problem in an installed Thunderbird software.