If you get an error about connection refused or blocked port before your email is delivered, this is due to your ISPs blocking the ability to use third-party email servers like 4Domain's. The following ISPs do this:

• AT&T
• Cox
• Earthlink
• MSN
• SBC
• Verizon

If this is the case, the options are to use port 587 for your outgoing email/SMTP port, use the webmail for your domain (available at http://webmail.your-domain.com), or use your ISP's SMTP server to send email.