Grey listing is a common spam filtering technique. The first time AgentSpam sees a ‘from’ email address it sends a ‘temporary error’ (a 4xx status code) to the sender. The sending email server attempts to re-send the mail (based on it’s retry rules) and mail is accepted on the second attempt. This email address is then cached for a rolling 72 hours so it won’t get grey listed again. This ensures that your most common recipients will only be grey listed once (the first time they email you).

Grey listing is very effective because most spammers do not try to resend mail.

Mail will queue on the AgentSpam cluster until your server is back up and on-line. AgentSpam follows ‘best practices’ on queuing mail. Mail will fail delivery if it can’t be delivered to your mail server after 4 days.

At the current time we can only deliver to one mail server.

No, you do not have to host your own mail server. AgentSpam sits between your incoming mail and your mail server (via MX records) so your mail can be hosted anywhere.

In essence the spam definitions are updated in near-real time. The definitions come from multiple sources as well as customer submitted information (releasing mail from the quarantine or submitting mail as spam).

No. By default AgentSpam will query your mail server to determine if the mailbox is valid. If it is AgentSpam will cache that information to reduce queries to your mail server. If the mailbox is invalid it is rejected.

We will provide the DNS records you need to use for AgentSpam. You will need to log in at your DNS provider to make the actual change. How it’s done varies from provider to provider. If you need specific directions, please open a support ticket.

You can use the log search facility to see if the mail reached the spam filter. If AgentSpam rejects an email the sender receives an immediate bounce, so typically they will know right away that the mail was rejected.

Mail is classified one of three ways:

1. Clean mail
2. Spam
3. Unknown

Clean mail is immediately delivered. Spam mail is immediately rejected. Unknown / questionable email is quarantined (held). If a new email is added to your quarantine you’ll get a quarantine digest email the next morning. The email contains the date/time of the email, the subject and the sender. If you believe the email is not spam there is a link to release it.Mail is held in the quarantine for 30 days.

No spam filtering solution is perfect so yes, you may get some false positives. When you release mail from the quarantine that trains the filter that the mail is not spam. When you submit mail that got through the filter that also trains the filter. We have plugins for both Thunderbird and Outlook that allows you to easily mark mail as spam.