Technical Standards for Email Delivery

The following technical requirements apply to the delivery of Internet email through AOL's email network.

  • AOL's servers will not accept connections from unsecured systems. These include open relays, open proxies, open routers, or any other system that has been determined to be available for unauthorised use.
  • AOL's mail servers will not accept connections from systems that use dynamically assigned or residential IP addresses.
  • AOL will not deliver email that contains a hex-encoded Universal Resource Locator (URL) (e.g. http://%6d%6e%3f/).
  • AOL's mail servers will reject connections from any IP address that does not have reverse DNS (a PTR record).
  • AOL may reject connections from servers whose recipient lists consistently generate a higher than 10% bounce failure rate (i.e. over 10% of a sender's mailing list is destined for users that do not exist on our system).
  • AOL may reject connections from senders who are unable to accept at least 90% of the bounce-return messages (mailer-daemon failure/error messages) destined for their systems.
  • Complaints submitted by AOL members will be used as a basis for refusing connections from any mail server.
  • AOL may provide daily communications to and (or @IP.address if no reverse-DNS or PTR records are present) to senders who may be in violation of AOL's guidelines.

For additional information on some of the terms discussed here, please visit the Information Centre.