The limitation in place
If you log into the pop3 server too often (i.e. more often than 60 seconds), the pop3 server will cut your connection on the server at one stroke.
This mechanism has been setup to avoid connection abuse on the pop3 server with anti-spam/virus softwares, or useless connection periods. Make sure that you don't have any software such as icq, which regurlarly check if there are new emails.
Here are the errors you could get:
The task «pop3.XXXXXXX - Reception has detected an error (0x800CCC0F): «The connection to the server has been stopped. If the problem persists, contact the administrator of the server or the Internet Service Provider.»
And what if I need to check my emails every 30 seconds?
If you need to check your emails more than every 60 seconds, you must redirect emails to a smtp server and use the softwares that can directly read emails saved on the smtp server (such as mutt).