A Directory Harvest Attack or DHA is a technique used by spammers in an attempt to find valid e-mail addresses. A spammer can easily generate a flood of messages to multiple addresses at (usually) a corporate email server. These servers are likely to have a standard format for official e-mail aliases (i.e., jdoe(at) company.com, johnd(at)company.com, or johndoe(at)company.com). Any addresses that do not generate a "message delivery failed" email are considered to be valid and are added to the spammer's list. Good anti spam software should be able to detect this flood of emails and quickly block the spammers from swamping the network.

As you can imagine, a whitelist is the opposite of a blacklist, i.e., it is a list of domains that send good email, not spam. An Automated Whitelist is a whitelist which is created or maintained by the anti spam software that monitors incoming and/or outgoing email, and based on your standards, will add or remove entries from the whitelist without you having to both

As you can imagine, a whitelist is the opposite of a blacklist, i.e., it is a list of domains that send good email, not spam. An Automated Whitelist is a whitelist which is created or maintained by the anti spam software that monitors incoming and/or outgoing email, and based on your standards, will add or remove entries from the whitelist without you having to both

As you can imagine, a whitelist is the opposite of a blacklist, i.e., it is a list of domains that send good email, not spam. An Automated Whitelist is a whitelist which is created or maintained by the anti spam software that monitors incoming and/or outgoing email, and based on your standards, will add or remove entries from the whitelist without you having to both

As you can imagine, a whitelist is the opposite of a blacklist, i.e., it is a list of domains that send good email, not spam. An Automated Whitelist is a whitelist which is created or maintained by the anti spam software that monitors incoming and/or outgoing email, and based on your standards, will add or remove entries from the whitelist without you having to both

Microsoft Exchange mail servers can compare the routing addresses of incoming emails to a list of servers that spammers are suspected to use. If an email appears to be from a blacklisted server, it is blocked.

The advantage to this kind of anti spam solution is that you don't have to install anti spam software; you just use a DNS blacklist to do the filtering for you.

The downside of this solution is that it can block legitimate email if the innocent bystander happens to share space on a server with the spammer -- guilt by association, if you will.

Similar to a DNS blacklist. The advantage to this kind of anti spam solution is that it is potentially more precise -- it blocks spam from a single URL instead from a single server that may host multiple URLs.

The d