I have been working with email servers since 2001, and registered my domain name in order to have my own personal domain. Over the years, I had to make various changes and updates. Today I switched internet providers and had to make some more changes.
SMTP port 25 blocked!
The first change came when I moved my server from a business class account to a residential account.
Not having a static address was not a major problem. The dynamic address from the ISP rarely changed, and when it did I would update the new IP address.
Having port 25 blocked however was a major issue. After some research, I decided to use No-IP's Alternate-port SMTP service. For a yearly fee, I can use their SMTP server as my domain's MX, and their server relays my mail to my server over port 2525 to get around the blocked port 25. I opened port 2525 on my router, and redirect it to port 25 on my server.
My next change was migrating to a dynamic DNS service. I moved, and signed up with a different ISP. Now my IP address was changing more frequently, and having to update my new address at No-IP became a problem. Again I decided to use No-IP because their Dynamic DNS service is free, and I'm already a customer. Having a FreeBSD Unix client in the ports collection made the integration easy and seamless.
Postfix and FreeBSD Unix
The next change was major. Back in 2001, the company I worked at used Exchange and IMail by Ipswitch. To remedy the problem of spammers using unknown email addresses to spam our servers, I implemented IMGate OpenSource Mail Firewall by Len Conrad- a Postfix server as an MX gateway server. I've been using Postfix and FreeBSD ever since!
Learning Unix and FreeBSD's implementation and configuration has been a slow process. I had dreams of adding Dovecot as my mail storage and IMAP/POP server using Maildir to replace IMail's Mbox. I struggled with this and kept the Windows 2000 server running to host IMail. I did succeed in getting Squirrel Mail up and running, to handle my web mail interface after IMail's web mail broke. (That is, until Squirrel Mail broke with an unsuccessful Port Upgrade!)
Last year, I found iRedMail. This was my Unix salvation! What iRedMail does is installs and configures Postfix with Dovecot, along with RoundCube for webmail. Start with a fresh Unix/Linux install (supports Redhat/CentOS, Debian, Ubuntu, OpenBSD and my favorite FreeBSD), run the iRedMail script to install mail server/mail store/database/web server and the rest. Then configure and season to taste- for me it was instant mail server! Now I could finally migrate and retire my Win2k box (which by now was running inside an Oracle VirtualBox hosted on a laptop running Windows 7 Home Edition! This VM configuration ran faster/quieter/cheaper than the Compaq dual 300mhz Pentium II server that was running my email since 2001)!
MXGuardDog as a spam prevention gateway
Even before implementing iRedMail, spam was a major problem for me. I had Amavisd-new installed and running on my Postfix server, stopping spam was a problem because of the No-IP mail relay.
More research on how to prevent spam, and I came across MXGuardDog. Tried it out, and spam dropped to practically zero! Plus, it could relay my mail to an alternate port meaning I can now stop using No-IP's Alternate-Port service (still use their Dynamic-DNS). They have a nice web interface to review the quarantined spam. A couple of clicks to verify any false positives and release it for delivery.
By adding some web links (like the shameless 'stopping spam' plug above) I can have free spam filtering and protection.
Finally, today's changes. New ISP with new modem, new router and firewall. And whereas the old router could redirect incomming port 2525 to my server port 25, the new router doesn't. Easy fix, edit the Postfix master.cf file and add an smtpd listener on port 2525.