Client software cannot send email at latest version of MIAB

Hi all
I have a problem with the new version of mailinabox.

I am using mailinabox for more than 2 years. for a new domain, I have installed the latest version of MIAB. in this version I cannot send emails from client software using pop3 or IMAP.

It means if I login at everything is ok. but in client software like windows 10 mail app I can only receive the mails and sending is impossible.
I have check firewall and open ports and configurations. everything seems fine.
no software works.

Does anyone test the latest version of MIAB? It seems like a bug in the last version.

Thanks for your support.

Neither protocol is used for sending email…

No, more likely your email client software is outdated. At the end of March, two TLS versions became End of Life. So that means that older email clients such as Microsoft Outlook 2010 and Outlook 2013 no longer function to send email as those versions use the outdated security.