LinuxForce, Inc.
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E-Mail Protection Functionality

  • Basic Functionality of the LinuxForce Email Protection Service
    • Exim4 mail server (port 25 and 587)
    • POP (Post Office Protocol) mail retrieval to users POP mail accounts
    • Password (poppassd) change server for Eudora, NUPOP, and squirrelmail
    • Incoming SMTP mail delivery to POP mail accounts and aliases to support routing of role accounts and multiple identities
    • Outgoing SMTP mail delivery service to users on your private LAN (Local Area Network)
    • Support for outgoing authenticated SMTP mail delivery service to users who provide their POP account username and password
    • Support for TLS (Transport Layer Security) to encrypt mail delivery (for exchange of e-mail with sites that support TLS)
    • Web Mail functionality provided by squirrelmail (SquirreIMail-Plugins)
  • A sampling of SMPT-time ACLs (Access Control Lists)
    • dns lookups (will cause a delay if misconfigured; the delays trigger some badly written spambots into triggering other ACLs
    • helo verification
    • check actual helo for forgery or if bare ip used (rfc violation)
    • check that helo was said before mail from:
    • accept relay hosts (if any)
    • accept authenticated senders
    • reject non-authenticated senders on port 587
    • defer dictionary attacks
    • reject invalid local email addresses
    • accept postmaster
    • reject mail pretending to be from a system account at our domain(s)
    • reject mail that says helo as the domain it is sending to
    • sender verify callouts
    • reject locally blacklisted hosts/senders/domains
    • accept relay hosts (MTA's (Mail Transport Agent))
    • greylist "suspicious" connections
    • Check RBL's (Realtime Blackhole List) and reject if listed too many times, greylist if listed at all
    • evaluate headers of email (reject if obvious forgeries or greylist if it feels "spammy")
    • heuristic rejection of spam-like email
    • reject DSN's (Delivery Status Notification) for role accounts
  • Content Filtering
    • mime tests (reject insecure file extensions, invalid formatting)
    • file type based rejection
    • ClamAV for anti-virus
      • Scanning into multiple archives
      • Mutated Aho Corasick algorithm (very fast scanning)
      • Multi-threading, autodetecting the number of CPU
    • Spamassasin for spam scanning
      • Score based, rather than single accept/fail rules
      • Network tests
      • Regular expression matches
      • Naive bayesian database

For more information on LinuxForce's email protection services, e-mail us or call us at 610-734-1900.

Follow this link to return to the Main Page on our E-Mail Protection services.

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