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→Spam and Hoax Email
The secure version of MIME, known as S/MIME, was developed to allow for the encrypted email transmission of data over public networks. S/MIME uses RSA based asymmetric encryption and is supported by most modern email client applications.
== Dealing with Spam and Hoax Email ==
Whilst it is impossible to arrive at exact numbers, it is widely believed that spam email now accounts for as much as 40% of all traffic on the internet. The time employees spend deleting unwanted spam messages is believed to cost businesses in the United States alone in excess of $2 billion. a year in terms of lost productivity.
Clearly spam email messages are a serious issue which must be addressed by system administrators and IT security employees. A number of solutions to the problem are available but none, unfortunately provide 100% certainty of either eliminating all spam, or guaranteeing that legitimate messages will not be incorrectly categorized as spam.
One solution is to subscribe to ''email blacklists''. These are services which maintain a registry of known spam senders which can be used to isolate spam messages. Unfortunatelymany spammers send email using the open relays of legitimate email servers thereby disguising their true identity and limiting the usefulness of email blacklists. Another option is to install spam filtering software which blocks spam based on algorithms which scan messages for patterns and word sequences which are common to spam messages. Once again, this solution is only partially effective, resulting in some spam making it through filters and some valid messages being tagged as spam (so called ''false positives''). A common and effective way to eliminate the volume of spam on the internet is for system administrators to shut down ''mail relaying''. Spammers often use programs which scan port 25 (the SMTP port) of systems connected to the internet looking for open relays. Having found an open relay they use this to send vast volumes of spam messages out. Such messages appear to originate from the system with the open relay (almost always a legitimate business with no connections to the spammer) thereby making it difficult to track down the spammer and minimizing the effectiveness of email blacklists.
