Who is your email provider? Do you check your email with a program on your computer such as Outlook Express or a webmail such as Gmail? Have you tried calling them and asking if there have been any problems with their mail servers. Are you a business with your own domain name? If so, what is it, so I can help you check for valid MX records and that you domain has not expired. Also, some smaller ISP's try to get their upgrades done and may have had some significant downtimes over the holidays.