Two solutions for Sendmail configuration

Many of my friends often make the mistake: "I have already added the IP address of the email server to access and makemap the database files, but it still doesn't work ". In fact, you are wrong. You should add the Client IP Address -- try to add the IP address of your dial-up PC to access. After makemap, you do not have to restart Sendmail, sent successfully!

As mentioned above, if you use dial-up Internet access, your IP address will change next time you dial up. Of course, your email server won't let you send emails again. If employees in the company are often on a business trip, after arriving in other places, they often call the local ISP to send and receive emails. There is certainly no problem in receiving emails. However, currently, SMTP does not verify the password of emails, and the mail server must control forwarding, so it does not forward hosts not recorded in the database. Therefore, emails cannot be sent. In this case, if you set all the forwarding functions as mentioned earlier in this article, you can send a mail to the dial-up user. However, there are also many Spam problems, it is really difficult to achieve the best of both worlds.

There are two solutions to solve Sendmail configuration. One is to adopt SMTP authentication, that is, before a user sends an email, the mail server authenticates the user's identity. If the user passes the authentication, the server sends the email to the user; otherwise, the mail is rejected; the second solution is to use the dynamic forwarding authorization control DynamicRelayauthorizationcontrol). The working principle is: after a dial-up user attempts to access the Internet, the user first receives the mail. If the user can receive the mail correctly, the DRAC automatically accesses the page. add the email recipient's IP address to the db and allow this IP address to send emails. However, if this IP address does not send or receive emails within 30 minutes, DRAC will delete this IP address from access. db. This mechanism ensures that the dial-up user can send e-mail details through the remote mail server without SMTP authentication. For more information, see the author's article: use DRAC to prevent spam ).