How to filter the sender of the message and only allow the company mailbox to send the message?

In order to meet the needs of information security, some enterprises need to supervise the sending and receiving of mail. For example: "only allowed to use the company mailbox to send mail, and record the contents of the company mailbox, so as to achieve management purposes."

In this article, I will show you how to use WFilter NGF's message filtering feature to impose whitelist restrictions on the senders of messages (only mailboxes in the whitelist are allowed to send messages). There are two options:

All web mail and client mail are prohibited. At the same time, add the IP address of the corporate mail server to the exception settings. (requires the company to have a special mail server)

If the company does not have a dedicated mail server, purchase and lease an open mail service. To filter mail, you need to use the mail filtering module in WFilter NGF.

In this article, I will describe the specific steps of the second approach in detail.

1. Only part of the mail sending and receiving protocol is allowed

Email sending and receiving protocols, in addition to the standard SMTP/IMAP/POP3, there are some private protocols, such as Lotusnote, NetEase flash mail and so on. In order to filter email senders, it is necessary to prohibit other private mail protocols and open only standard protocols. As shown below:

In the Application filtering module, set these mail protocols to allow: send mail (SMTP), receive mail (POP3), receive mail (IMAP), SMTP send messages with attachments, SMTP send mixed format messages, and SSL encrypted SMTP/POP3/IMAP.

two。 Block all web mail

Web mail is a private protocol, so it is impossible to filter email addresses, so it is necessary to ban all web mail. As shown below:

Using the URL library function in WFilter NGF, you can disable most of the "web e-mail".

3. Enable SSL email monitoring

If the client mail is SSL mail (with "SSL" connection checked), you also need to turn on "SSL Monitoring" on the mail protocol in order to achieve content monitoring and mail filtering. As shown below:

4. Turn on the "sender whitelist" of email filtering

In message filtering, open the "sender whitelist". Only mailboxes in the whitelist can send messages. As shown in the figure:

5. Effect test

When a client message is sent with a mailbox that is not in the whitelist, a failure is sent with an error message. As shown in the figure:

In the real-time blocking of WFilter, you can see the blocking records, as well as the banned email accounts.

6. Matters needing attention

NetEase's own email client (NetEase Flash Mail, NetEase mailbox master) will use NetEase's private email protocol to bypass filtering when sending mail under 163Universe 126. Therefore, it is necessary to block NetEase's private email protocol in the "application filtering".