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I'm having a horrible issue with spam but only for a few users which I am surprised by because usually the spammers attack the domain so I am wondering if I make the setting in exchange on a user under Recipient configuration, Mailbox Message Delivery Restrictions Check the box that says Require that all senders are authenticated if that will stop the spam and if not, why and if so why? &nbsp;Thank you in advance.<br />
<a href="https://filedb.experts-exchange.com/incoming/2015/12_w51/1054725/Screenshot_3.png" target="_blank" title="Screenshot_3.png (39 KB)"><img alt="Screenshot_3.png" class="file-block lazyload" style="max-width: 661px;" data-src="https://filedb.experts-exchange.com/incoming/2015/12_w51/1054725/Screenshot_3.png" /></a><a href="https://filedb.experts-exchange.com/incoming/2015/12_w51/1054723/Screenshot_1.png" target="_blank" title="Screenshot_1.png (84 KB)"><img alt="Screenshot_1.png" class="file-block lazyload" style="max-width: 800px;" data-src="https://filedb.experts-exchange.com/incoming/2015/12_w51/800_1054723/Screenshot_1.png" /></a>
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I'm having a horrible issue with spam but only for a few users which I am surprised by because usually the spammers attack the domain so I am wondering if I make the setting in exchange on a user under Recipient configuration, Mailbox Message Delivery Restrictions Check the box that says Require that all senders are authenticated if that will stop the spam and if not, why and if so why?  Thank you in advance.



Exchange

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Various techniques are used to prevent email spam (unsolicited bulk email). No technique is a complete solution to the spam problem, and each has trade-offs between incorrectly rejecting legitimate email (false positives) vs. not rejecting all spam (false negatives) - and the associated costs in time and effort. Anti-spam techniques can be broken into four broad categories: those that require actions by individuals, those that can be automated by email administrators, those that can be automated by email senders and those employed by researchers and law enforcement officials.

AntiSpam

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.