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How to debug Cyrus-imap?

Cyrus-imap is an error-prone program. To debug it, you need to edit /etc/imap.conf to add “debug:1″ and create a user directory in /var/log/imap/log/admin to log the protocol messages. You need to know the log sequences for successful cases: Sep 14

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How to use openssl to connect to a pop3 server and retrieve emails?

openssl s_client -connect user pass yourpassword stat (show total messages and size of the messages) list (show each message on a new line, including message number and the size of the message) retr messagenumber (retrieve the content of

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VPNs that block port 25

You may be looking for VPNs that open outgoing port 25. The famous VPN providers won’t tell you on their homepage they have blocked outgoing port 25 for preventing from spamming. You may have to buy one VPN after another

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How to enable htaccess in apache?

When I migrated my website from CentOS 6 to CentOS 7, I found the wordpress site stopped working. Only the homepage can be displayed, other internal pages of the website “are not found”. Even the homepage is not displayed properly

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Why PTR record is important for email delivery?

PTR record(or pointer recored, or RDNS record) is a DNS record in a DNS zone file. It maps an ip address to a host name or a domain name. It is used by mail servers to fight spammers. It is

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environment variable in linux

How to set an environment variable in Linux? You must know how to set a variable in bash:

You can show its value using:

  However, the bash variable is not an environment variable. The different between ordinary

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Intall software from installation disk of CentOS

I have been using CentOS on my VPS. Today I need to install CentOS 7 on my PC. The installation process was not smooth and I had to do it in text mode. The main task during the installation is

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How to embed images in an email?

We know that in html, an image is embedded with an img tag like <img src=”image.jpeg”/>. We put the image file name in the src attribute of the img tag. In email, however, there is no such concept as file.

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WordPress upgrade cheat sheet

I never upgraded wordpress before because I’m afraid the upgrade may break existing functionalities of my site. So I always add the following line to wp-config.php:

AUTOMATIC_UPDATER_DISABLED will prevent wordpress site from upgrading itself automatically. The result isĀ  when

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How to prevent email going to spam?

Nowadays, it is hard to prevent email from going to junk mail if you intend to spam. Most mail servers on the internet deploy spam detection and filtering software that use complex algorithms to detect spammers. The software can tell

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