How reliable is email?
Posted in Messaging by Ben Christian on January 28th, 2006 How reliable is email? I get that question alot from users, and in recent times I’ve had to tell them that it’s not very reliable at all. There’s no doubt that spam is to blame; several years ago I beleived that email was reliable - you could realistly expect that if you addressed a message properly that the recipient would receive it, if not you’d receive a mail failure.
In Fred Langa’s experiement he found a 40% failure rate for valid, non-spam emails. Based on his findings, Fred concludes that spam filters are often to blame. Over-sensitive spam filters are definitely the main cause for most lost mail, and the problem is that if a message is blocked as spam, the sender won’t receive a mail failure and therefore is unaware that the message never got to the intended recipient.
The other problem however is that spam has bred a culture of ‘delete key happy’ users; if an email looks like spam then it’s probably going to get deleted, and in alot of cases it will be deleted without being opened at all. Although spam filters appear to be the main cause for lost email, the human element is starting to play a large role too. I’ve come across cases where users have asked me to track down an email that “they never received”; after checking the mail gateway where our filtering takes place, and performing an Exchange message tracking center search, I’ve discovered that the message was in fact delivered to their mailbox. Take a quick look in either their deleted items or the items that have been permantely deleted from their mailbox (retreivable by using the DumpsterAlwaysOn reg key) and its not rare to find the message that was “never received”. Usually in these cases the user was not actually expecting the message and the subject looked like spam so they deleted it. Afterwards, the sender has told them that they sent them a message but the user doesn’t make the connection between the message that they deleted and the message that they are now expecting to have received.
While there are efforts by various vendors and groups to improve SMTP (like Microsoft’s Sender ID for example) I think it will be a while yet before internet mail will be reliable and trustworthy.
