550 Access Denied
The biggest problems with getting your Email to someone is getting through the receiving ends mail servers defences.
Sadly, long gone are the days of the early 90's where spam was really only something that was heard of in a supermarket, although it had been around for years, even on ARPANET, it was not of plague proportions like it reached in the mid-late 90's through to the problem it is today. Long gone also are the days where you can trust strangers to use your mail server, where it was common two decades ago for most mail servers to be open relays, but, as with anything that's available, it soon became abused, so to combat the problem of spammers abusing this privilege, MTA's like Sendmail soon released versions that no more by default permitted open relaying capabilities, like the 'ol saying... if you abuse it, you loose it!

Defence comes in many forms, most common is the well known method of DNSBL's (DNS based Real-time Block Lists), often also referred to as RBL's, PBL's, Blacklists, or even Blackhole Lists, these are DNS based lists of domain names and IP numbers of trouble makers, people who have given others grief in some form or another (spam, phishing, compromised, abuse, etc...), they become submitted to these lists by trusted persons, also through automated processes, including hidden addresses to trap spambots when they harvest websites looking for addresses to add to their spam-out lists.
Continue reading "550 Access Denied"
Sadly, long gone are the days of the early 90's where spam was really only something that was heard of in a supermarket, although it had been around for years, even on ARPANET, it was not of plague proportions like it reached in the mid-late 90's through to the problem it is today. Long gone also are the days where you can trust strangers to use your mail server, where it was common two decades ago for most mail servers to be open relays, but, as with anything that's available, it soon became abused, so to combat the problem of spammers abusing this privilege, MTA's like Sendmail soon released versions that no more by default permitted open relaying capabilities, like the 'ol saying... if you abuse it, you loose it!

Defence comes in many forms, most common is the well known method of DNSBL's (DNS based Real-time Block Lists), often also referred to as RBL's, PBL's, Blacklists, or even Blackhole Lists, these are DNS based lists of domain names and IP numbers of trouble makers, people who have given others grief in some form or another (spam, phishing, compromised, abuse, etc...), they become submitted to these lists by trusted persons, also through automated processes, including hidden addresses to trap spambots when they harvest websites looking for addresses to add to their spam-out lists.
Continue reading "550 Access Denied"