Postfix: Configuring Gmail as Relay – matthew hawthorne is mhawthorne.net http://mhawthorne.net/posts/postfix-configuring-gmail-as-relay.html
12.04 – How can I configure Postfix to send all email through my Gmail account? – Ask Ubuntu http://askubuntu.com/questions/228938/how-can-i-configure-postfix-to-send-all-email-through-my-gmail-account
Configure Postfix to Use Gmail SMTP on Ubuntu – EasyEngine https://easyengine.io/tutorials/linux/ubuntu-postfix-gmail-smtp/
Email sent to gmail is flagged as spam. | DigitalOcean https://www.digitalocean.com/community/questions/email-sent-to-gmail-is-flagged-as-spam
How To Install and Configure Postfix as a Send-Only SMTP Server on Ubuntu 14.04 | DigitalOcean https://www.digitalocean.com/community/tutorials/how-to-install-and-configure-postfix-as-a-send-only-smtp-server-on-ubuntu-14-04
How To Install the Send-Only Mail Server “Exim” on Ubuntu 12.04 https://www.digitalocean.com/community/tutorials/how-to-install-the-send-only-mail-server-exim-on-ubuntu-12-04
10.04 – How can I disable postfix on startup? – Ask Ubuntu http://askubuntu.com/questions/231402/how-can-i-disable-postfix-on-startup
Setting the Hostname & Fully Qualified Domain Name (FQDN) on Ubuntu 12.04 or CentOS 6.4 https://github.com/DigitalOcean-User-Projects/Articles-and-Tutorials/blob/master/set_hostname_fqdn_on_ubuntu_centos.md
How to include multiple domains in an spf TXT Record – Server Fault http://serverfault.com/questions/283125/how-to-include-multiple-domains-in-an-spf-txt-record
Questions & Answers | DigitalOcean https://www.digitalocean.com/community/questions/?q=SPF&primary_filter=newest
How To Install Webmin with SSL on Ubuntu 14.04 | DigitalOcean https://www.digitalocean.com/community/tutorials/how-to-install-webmin-with-ssl-on-ubuntu-14-04
How To Install Linux, Apache, MySQL, PHP (LAMP) stack on Ubuntu 14.04 | DigitalOcean https://www.digitalocean.com/community/tutorials/how-to-install-linux-apache-mysql-php-lamp-stack-on-ubuntu-14-04
How to change virtual root from /home to /var/www/vhosts? | Virtualmin https://www.virtualmin.com/node/10150
Virtualmin Suexec Error /var/www/vhosts – The Portland Company https://www.theportlandcompany.com/2014/01/virtualmin-suexec-error-varwwwvhosts/
How can I make ssh ignore .ssh/config? – Unix & Linux Stack Exchange http://unix.stackexchange.com/questions/110283/how-can-i-make-ssh-ignore-ssh-config
Manage multiple SSH private keys with IdentityFile « Bongo’s Codeways http://www.kelvinwong.ca/2011/03/30/multiple-ssh-private-keys-identityfile/
Automating removal of SSH key patterns | End Point Blog http://blog.endpoint.com/2012/01/automating-removal-of-ssh-key-patterns.html
git – Best way to use multiple ssh private keys on one client – Stack Overflow http://stackoverflow.com/questions/2419566/best-way-to-use-multiple-ssh-private-keys-on-one-client
rebuild vs restore | DigitalOcean https://www.digitalocean.com/community/questions/rebuild-vs-restore
Frequently Asked Questions – Technical | DigitalOcean https://www.digitalocean.com/help/technical/setup/
Options Used within iptables Commands https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/3/html/Reference_Guide/s1-iptables-options.html
How To Set Up a Firewall Using Iptables on Ubuntu 14.04 | DigitalOcean https://www.digitalocean.com/community/tutorials/how-to-set-up-a-firewall-using-iptables-on-ubuntu-14-04
How To Choose an Effective Firewall Policy to Secure your Servers | DigitalOcean https://www.digitalocean.com/community/tutorials/how-to-choose-an-effective-firewall-policy-to-secure-your-servers
How To List and Delete Iptables Firewall Rules | DigitalOcean https://www.digitalocean.com/community/tutorials/how-to-list-and-delete-iptables-firewall-rules
Minimal Iptables Configuration – Developer Should Know http://developer-should-know.tumblr.com/post/128018906292/minimal-iptables-configuration
How To Use RKHunter to Guard Against Rootkits on an Ubuntu VPS https://www.digitalocean.com/community/tutorials/how-to-use-rkhunter-to-guard-against-rootkits-on-an-ubuntu-vps
Setup mail server on ubuntu 14.04 ( Postfix – dovecot ) http://www.krizna.com/ubuntu/setup-mail-server-ubuntu-14-04/
An In-Depth Guide to mod_rewrite for Apache – Envato Tuts+ Code Tutorial http://code.tutsplus.com/tutorials/an-in-depth-guide-to-mod_rewrite-for-apache–net-6708