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PHP Send Email

Q. How do I send an email using PHP and Apache webserver under Linux / UNIX operating systems? How do I send email from a PHP Script?
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Q. How do I force apt-get to send me email when upgrades or security updates available under Debian or Ubuntu Linux? Do I need to write a shell script which generates a mail with a list of all packages currently pending an upgrade?
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DNS Name Resolution

Q. Can you explain DNS name resolution concept? Why I need to set DNS resolution for my Windows or Linux server? How do I setup DNS name resolution under Linux / UNIX server system?
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Bind Postfix Mail Server To Localhost or Specific IP Address Only

Q. How do I bind Postfix MTA to specific IP address such as or
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Q. I've recently changed email user account password using passwd command, for one my postfix email server which requires SMTP authentication before sending an email. Now following error is logged into my /var/log/maillog file:

ERROR: Password not accepted from server: 535 5.7.0 Error: authentication failed: authentication failure

How do I solve this problem under Red Hat enterprise Linux running Postfix with SASL authentication?
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Linux Restart IMAP Services ( dovecot IMAP server )

How do I restart dovecot IMAP4 / IMAP (Internet Message Access Protocol) under RHEL / CentOS / Fedora / Debian / Ubutnu Linux?
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Dedicated Server Hosting

Q. We have decided to move to Linux and brought a dedicated Dell server preinstalled with Red Hat Linux for hosting our small business website. Can you tell me what software required to run on a Linux dedicated server for hosting purpose?
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Mail delivery: DNS: Service unavailable error

Q. My mail delivery fails with DNS: Service unavailable error. How do I fix this error under Linux / UNIX operating systems?
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Linux Mail Delivery Failed With DNS Service Unavailable Error and Solution

Q. I get following error message for my postfix email server:

Mail Delivery Failed With DNS Service Unavailable Error and Solution

How do I fix this problem?
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Linux Demilitarized Zone (DMZ) Ethernet Interface Requirements and Configuration

Q. Can you tell me more about Linux Demilitarized Zone and Ethernet Interface Card Requirements for typical DMZ implementation? How can a rule be set to route traffic to certain machines on a DMZ for HTTP or SMTP?

A. Demilitarized zone, used to secure an internal network from external access. You can use Linux firewall to create DMZ easily. There are many different ways to design a network with a DMZ. The basic method is to use a single Linux firewall with 3 Ethernet cards. The following simple example discusses DMZ setup and forwarding public traffic to internal servers.
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