Spamdyke is a spam protection program that filters incoming messages at the SMTP level by blocking connections from mail servers identified as spam sources or that match certain reverse DNS validation rules and RBL Checklists.

2Large Networks uses the following methods to determine whether a sending server can be identified as a spam source:

1. Reverse DNS check
Every server on the internet should have a reverse DNS entry, especially mail servers.

Our mail server checks for reverse DNS entries. Any email coming from a server without one is blocked. This stops a lot of email from servers that shouldn't be sending email, such as virus-infected home computers on ADSL connections.

2. RBL Checks (Lists of known spam hosts).
Spamdyke checks the sending server IP address against several databases of known spam hosts. In case the sending server IP is listed in any of them, the message is blocked.

3. Check for no mail exchanger, making the sender address invalid.

If you have recieved any of the following email notifications while sending to a 2large Networks server
Please contact us to resolve this issue for you as quick as possible.
syslog code SMTP message
DENIED_ACCESS_DENIED Refused. Access is denied.
DENIED_AUTH_REQUIRED Refused. Authentication is required to send mail.
DENIED_BLACKLIST_IP Refused. Your IP address is blacklisted.
DENIED_BLACKLIST_NAME Refused. Your domain name is blacklisted.
DENIED_EARLYTALKER Refused. You are not following the SMTP protocol.
DENIED_OTHER The text returned by qmail (or the downstream filter that generated the rejection).
You rmail has been blocked by a Spamassassin filter.
DENIED_RDNS_MISSING Refused. You have no reverse DNS entry.
DENIED_RDNS_RESOLVE Refused. Your reverse DNS entry does not resolve.
DENIED_RHSBL_MATCH The text returned by the RHSBL (if any) or
Refused. Your domain name is listed in the RHSBL at name.
DENIED_RECIPIENT_BLACKLISTED Refused. Mail is not being accepted at this address.
DENIED_SENDER_BLACKLISTED Refused. Your sender address has been blacklisted.
DENIED_SENDER_NO_MX Refused. The domain of your sender address has no mail exchanger (MX).
DENIED_TOO_MANY_RECIPIENTS Too many recipients. Try the remaining addresses again later.
Max recipients is set to 50
DENIED_UNQUALIFIED_RECIPIENT Improper recipient address. Try supplying a domain name.
DENIED_ZERO_RECIPIENTS Refused. You must specify at least one valid recipient.
TIMEOUT Timeout. Talk faster next time - your SMTP connection is too slow.
UNKNOWN_AUTH Refused. Unknown authentication method.