Very slow connection to imap.263.net

Hi,
I try the latest version to connect our company email system:
imap.263.net / 993 (overseas: imapw.263.net)
smtp.263.net / 465 (overseas: smtpw.263.net)

It’s very slow to download the emails compared with my connections by using new outlook (automatic detection) or thunderbird or foxmail (our email domain [email protected]). Very strange.

Any helpful instructions?
Thanks,
Baron

I would say it failed to download all emails, even worse than slow…