No filter is perfect.
Please keep your virus scanner up to date and never open unexpected or suspicious attachments.
Our customers are placed into our most secure filtering configuration by default.
This means that inbound E-mail addressed to them must pass the following tests:
1. Our Blacklist: IP addresses that have abused us twice in the last 48 hours are blocked.
2. Greylisting: Items from a list of known-good Internet mail servers are accepted.
3. Spamhaus XBL and SBL: IPs in this well-known list of Spam sources are blocked.
4. Backscatter Filtering: This stops bogus "non-delivery notices" that may carry malicious payloads.
5. Clam Antivirus: This is an up-to-date virus scanner that even scans inside archived attachments.
6. Spamassassin: This is a program that "reads" the Email and scores it based on words or phrases.
7. Perlscan: This looks for dangerous attachments and broken Email headers.
Customers may bypass any or all of these tests. In addition, they may use Spamassassin, but modify the scoring. To help customers make a good decision, we provide a page on the pros and cons of each filter.
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