Blog Archives

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

Posted in tips of hosting

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

Posted in tips of hosting

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

Posted in tips of hosting

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

Posted in tips of hosting

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

Posted in tips of hosting

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

Posted in tips of hosting

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.

Posted in tips of hosting

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

Posted in tips of hosting

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

Posted in tips of hosting

How to add a DKIM record to DNS?

Adding a DKIM record is more complicated than adding a SPF record because it needs to create a public/private key pairs and it also needs to install a DKIM software and configure your mail server to cooperate with the DKIM

Posted in tips of hosting