Network Analysis Using Wireshark 2 Cookbook - Second Edition
by Nagendra Kumar Nainar, Yoram Orzach, Yogesh Ramdoss
How it works...
Most email servers support spam and junk message detection, and dynamically create filter rules for such emails. Servers also support customizing such rules based on sender/receiver mail address, or based on domain and IP.
When the server receives a mail from an internal client using IMAP/POP3, or from an external server using SMTP, it checks the local filters and forwards it to the respective inbox if the rules allow it to do so. If any rule matches certain attributes or metadata in the mail, the server will filter the message.
On the email client, we can optionally have email-scanning software for more rigid security. Such software will perform additional checks on the client side and mark it as spam or malicious, and warn ...
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