SMTP status codes

Have you ever wondered what all those SMTP status codes mean? It’s not that hard to read. Each code consists of three numbers. The format for this is class.subject.detail, for example 2.5.0 (also written as 250).

Here is a list of the classes:

2.x.x - Succes
4.x.x - Temporary failure
5.x.x - Permanent failure

Here are the subjects:

x.0.x - Other or undefined
x.1.x - Addressing related
x.2.x - Mailbox related
x.3.x - Mail system related
x.4.x - Network or routing related
x.5.x - Mail delivery protocol related
x.6.x - Message content related
x.7.x - Security or policy related

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Cisco VPN – Error 51

All weekend I have been having trouble connecting to my work’s VPN on OS X 10.5 (Leopard). My favourite VPN client, Shimo, doesn’t even want to try, and the Cisco VPN client gives me this error:

Cisco VPN - Fix for Error 51: Unable to communicate with the VPN subsystem

All it is, is the Cisco VPN service needing a restart. Open a terminal and type:

$ sudo /System/Library/StartupItems/CiscoVPN/CiscoVPN restart

Make Apple Mail display plain text

Some of us prefer our mail clients to display mails in plain text. Here’s how to set it.  Open ~/Library/Preferences/com.apple.mail.plist, click on the Root key, click “Add Item.”  Call it ‘PreferPlainText’ and set the type to boolean.  This gives you a checkbox to enable or disable it.

You can also do it via the terminal:

defaults write com.apple.mail PreferPlainText -bool TRUE

Or to disable:

defaults write com.apple.mail PreferPlainText -bool FALSE