Dovecot v2.3.7 - TLS/SSL issue

I use a helpdesk system that connects to dovecot using POP3 with SSL enabled to fetch the e-mails.

After I upgrade to v2.3.7 the helpdesk randomly (some times it works, some times not) doesn't fetch the e-mails. If I configure the e-mail accounts with SSL/TLS disabled then it works.

Any idea about this?