Protecting against spam

In order to minimize the amount of spam being received, the following actions are suggested:

• Do not have a catch-all set for domains. Spammers will make up email addresses for the domains hosted and try to send to them.
• Enable the setting 'Reject mail if sender address is from an invalid domain' . This is in the SMTP connector properties. This will stop the mail server from accepting email from people who have put an invalid domain as their From address.
• Enable the option for requiring that those sending mail to the server have a DNS PTR record defined for the IP address of their mail server. This setting is configured under the properties of the SMTP connector in the MailEnable Administration Program. Not having a PTR record usually indicates that the sender is on a dial-up/cable/ADSL connection. 
• Enable the option to require that anyone sending from a locally hosted e-mail address needs to authenticate. This prevents spammers from using your local envelope sender to send spam to other users on your server. This setting is configured under the properties of the SMTP connector in the MailEnable Administration Program.
• Configure the SMTP connector to use 1-2 RDNS blacklist providers; since this will prevent you receiving spam from known spammer IP addresses.
• If using MailEnable Enterprise Edition 2.0 or later, enable the URL blacklisting option, since it will scan messages for URLs that are known to be spam links. 
• Enable MailEnable's Sender Policy Framework (Professional and Enterprise Editions only). This setting is also configured under the properties of the SMTP Connector in the MailEnable Administration program.
• Bayesian Filtering is a self learning spam system that uses complex algorithms to detect spam by comparing message content against a dictionary. All filtering actions can be executed on the Bayesian criteria being met.
• If using MailEnable Professional or Enterprise Editions, configure one or more filters containing known spam term or word patterns. For example, a filter containing terms like Viagra (and combinations thereof using wildcards or text patterns) will catch mainstream spam.
• There are several dedicated third party anti-spam solutions that can be used to complement MailEnable's integrated spam blocking and content filtering. These are outlined here: Article ME020344

- Bayesian filtering

- Sender Policy Framework

- Relay Settings

- SMTP Authentication

- Reverse DNS Blacklisting

- Message filtering