Quick! Call Crimestoppers!! Somebody has pinched some of the days from this week!!
Been a busy week – been doing a lot of work on my hosting platforms. Some of it was housekeeping and things on the to-do list (consolidation and decommisioning of older kit) but the biggest problem has been dictionary spam attacks against some of the domains I host.
Mail is being delivered to random addresses at the domain, which then bounces the email as per RFC 821. But the from: addresses are spoofed so, in effect, the bounce becomes another spam to a server that wasn’t the actual originator. The bounce email is often bounced back (called a double-bounce) or rejected by the destination server, compounding the problem as it creates two or three extra emails for each spam message.
One of the domains in question has been receiving over 20,000 rogue emails per day and I have been forced blackhole emails to unknown email addresses. If I hadn’t, it would have receieved well over two or three times that many because of the bounces.
As an aside, RFC 821 was written in 1982, making the SMTP mail system 23 years old. Hats off to the late, great Jon Postel for creating something so flexible and robust that it still in use, virtually unchanged, today.