The TechMail system uses Microsoft Exchange Online (Microsoft 365). Exchange Online includes a feature called Sender Reputation. Sender Reputation filtering is an intelligent feature of email systems which receive email from the Internet. This feature determines the likelihood that a mail system is sending large amounts of unsolicited email or email that is harmful to the Internet and other email systems. It does this by testing the validity of the sending mail system's IP address, testing for open proxies, using black lists, and actively monitoring the history of messages sent from that system.

Systems that exceed a particular threshold will be blocked from sending email to the receiving system for a certain time period. That time period can vary, and for security reasons it is not revealed publicly. Also worth noting is that the sending server may become blocked again if its reputation score continues to be less than acceptable. In other words, the technology is "intelligent" and makes changes on its own based on information obtained from constant monitoring. When no spam is observed from the offending mail systems, the block will be automatically removed after a period of time; TechMail admins do not manually remove IP address blocks.

Many email systems use solutions similar to the Sender Reputation feature found in Microsoft Exchange.

While there is no perfect solution to stop all junk email, the Sender Reputation feature (when combined with other intelligent filtering solutions) will help improve your email experience and reduce the amount of junk email you receive.