If you are having problems collecting your mail through your usual mail software, try logging on to your webmail and then deleting and unwanted mail before trying your mail software again.
To logon to webmail, go to your web browser and in the address field type in www.yourdomain.co.za/webmail, the yourdomain bit is the bit after the @ sign of your e-mail address i.e.my domain is handshake so I would go to www.handshake.co.za/webmail, a window will now pop-up which asks for your User Name and Password. Your User Name is your full e-mail address, your password I hope you know or have written down someplace.
Once you are logged in select Squirrelmail and you should be able to see your mail.