This could be a DNS issue. If you just signed up yesterday things may not have propiagted yet. What error are you getting? How are you connecting? (IMAP or POP?) Give us a few more details so we can help.
Also, support can take a bit to get back to you sometimes. They strive to answer all E-mails within 24 hours. Normally for it only takes about 2 hours, but sometimes longer. They will answer your ticket, fear not.