In addition to the filter specified in other sections of the website, SpamFilter ISP supports several more filters that can be used to detect spam.
A partial list is below.
- Local IP Blacklist - Our SPAM Filter server checks if the remote server's IP address matches an entry in your local IP blacklist file, the email is rejected.
- Local Domain Blacklist - The SPAM Filter gateway checks if the domain portion in the sender's email address is in your local domain blacklist file, the email is also rejected.
- Local FROM EMail Blacklist - The sender's email address is checked against your local list of blacklisted email addresses. If present, it is rejected.
- Local TO EMail Blacklist - The recipient's email address is checked against your local list of blacklisted email addresses. If present, it is rejected.
- Attachment Blocking - SPAM Filter can check emails for specific attachments or attachment extensions. If found, the email is rejected.
- Keyword Content Filtering - Our SPAM Filtering software can check email content and subject for specific keyword and/or phrases. If found, the email is rejected.
- Honeypot Emails - You can have a list of "honeypot" email addresses. Any email sent to an address in the list will cause the sender's IP to be blacklisted.
- Connections can be rejected if the remote server does not have a reverse DNS PTR entry.
- Spam Filter is able to check if the sender's MX DNS record is valid before accepting email.
- Refuse connections if there are too many spaces in the subject line.
- Max Recipients in single session - Use this setting to limit how many RCPT TO commands can be issued in a single session.
- Max Email Size - Incoming emails can be blocked if they exceed a certain size.
- Reject if Empty "Mail From" - If this option is checked SPAMFilter will reject all emails with an empty "Mail From" field.
- Reject if "Mail From" = "Mail To" - Reject all emails where the sender's email is the same as the recipient's email.
- Reject if "From Domain" = "To Domain" - SPAM Filter can reject all email where the sender's domain is the same as the recipient's domain.
- Tag Spam & Deliver - Allows to tag spam by adding the header "X-SF-SPAM:Y" to email classified as spam. The email is then forwarded to the destination SMTP server. This allows administrators to handle spam as they wish on the back-end.
- Tag Spam in Subject & Deliver - Allows to tag spam by prefixing the word SPAM: in the subject line of emails classified as spam. The email is then forwarded to the destination SMTP server. This allows administrators to handle spam as they wish on the back-end.