Wednesday, December 26, 2007

A warm helo & ehlo to everyone...

On my first blog posting.... I realize, most people do not know what "helo" and "ehlo" mean. So picking a blog name with this might not be the smartest marketing idea, but I'm not so concerned with that (more important to educate folks at least a little bit). So, Without either term (helo & ehlo), email would not work as it does. Meaning, no email would be sent or received. So, maybe you should read the next paragraph to under a bit more.

All email servers communicate using either term (technically, this is how the initiating server starts communicating with another mail server). "helo" is the term for saying hello to another server when the initiating server is not very sophisticated and just wants to perform a basic email send communication. More sophisticated servers that support more features (aka extensions) and wish to use them (e.g. security, reliability, speed, etc), start off with "ehlo", also meaning hello, but also "tell me what commands" you support. This allows the other server to know, that this server can support x feature and will respond to handle it and perform the email communication in the enhanced manner.

So, of course my favorite email server, Microsoft Exchange Server (2003 currently) supports this feature & so does my favorite email gateway server (IceWarp's Merak Mail Server v.8.x). Unfortunately, some folks use firewalls to block (aka proxy) smtp commands, which can slow down email flow and prevent the use of ehlo. So, I recommend disabling such smtp firewall features (e.g. Cisco's fixup protocol) since this is a false sense of security and slows down communication. I've also had not heard of a security risk for smtp or other used commands on Exchange & Merak. So, this is not a real risk in my book (I tend to error on the side of security, so if I thought it was a danger, I would not suggest it). The benefits of "ehlo" outweigh any theoretical risk. So, enough of the soap box for this blog posting. I'll step down...

So, my plans for the future: the blog will tend to focus on a number of topics since I am interested in such, email in general in relation to server-side spam filtering techniques, email security, and performance, Microsoft Exchange Server, wireless (e.g. 802.11a/b/g/n), physical security, and other technology related things I get involved with.