The following technical requirements apply to the delivery of Internet e-mail through VailNet's's e-mail network.

VailNet's's mail servers will reject connections from any IP address that does not have reverse DNS (a PTR record) or from any system whose reverse DNS (PTR record) doesn't then resolve forward to an IP address. If you are trying to send an email to a vail.net mail server, but its being rejected with the error message " Client host rejected: cannot find your hostname" then either the DNS server for the host which was trying to send mail to you was down or that DNS server was not setup to correctly map the IP address of that mail server back to a valid hostname. For information about this and who to contact to resolve it see this web page

VailNet's's servers will not accept connections from unsecured systems. These include open relays, open proxies, open routers, or any other system that has been determined to be available for unauthorized use. Such system
shall include, but not be limited to, those actively listed in various blackhole lists like spamcop.net and/or spamhaus.org.

VailNet's may reject connections from servers whose recipient lists consistently generate a higher than 10% bounce failure rate. (i.e. over 10% of a sender's mailing list is destined for users that do not exist on our system)

VailNet's may reject connections from senders who are unable to accept at least 90% of the bounce-return messages (mailer-daemon failure/error messages) destined for their systems.

Transmitting Unsolicited commercial email/Unsolicited bulk email/email address harvesting. Using the Services to transmit any unsolicited commercial email or unsolicited bulk email. The sending of unsolicited commercial email or
unsolicited bulk email, whether or not that email is commercial in nature, is strictly prohibited and is grounds for immediate termination of Services. Any email sent through VailNet’s mail servers must conform to the Colorado State
anti-spam statute (House Bill 1309), which can be found at http://www.spamlaws.com/state/co.html. Email sent, or caused to be sent, to or through VailNet’s network that makes use of or contains invalid or forged headers, “made up” return addresses that are not email addresses of the Subscriber, invalid or non-existent domain names or other means of deceptive addressing will be deemed to be counterfeit. Attempts to email to multiple recipients that do no exist or have never existed on a system which slow down or interfere with legitimate email are also a violation of this policy. Any attempt to send or cause such counterfeit e-mail to be sent to or through VailNet is unauthorized. Similarly, attempts to relay e-mail through any third party's mail servers without the permission or knowledge of that third party, or which employs similar techniques to hide or obscure the source of the e-mail, is also an unauthorized use of the VailNet’s network. VailNet does not authorize anyone to send e-mail or cause e-mail to be sent to or through VailNet’s Network that violates our Terms of Service. VailNet does not authorize the harvesting or collection of email addresses for the purpose of sending unsolicited e-mail. VailNet reserves the right to take all legal and technical steps available to prevent the transmission of or reception of unsolicited bulk e-mail or other unauthorized e-mail from entering, utilizing or remaining within VailNet’s Network. Nothing in this policy is intended to grant any right to transmit or send e-mail to, or through, VailNet’s network. VailNet reserves the right to block or terminate any email transmissions or computer hosts which are the source of such transmissions in order to protect its network and systems. VailNet's failure to enforce this policy in every instance in which it might have application does not amount to a waiver of
VailNet's rights.