Telnet

Basic email delivery using telnet

• steve
• Delivery improvement

Whenever we’re working with someone to diagnose some obscure delivery issue one of the things we usually have them try is to “run a transaction by hand”. Being able to do that is a trick that everyone working with email should be able to do. I was drafting a blog post today and wanted to refer to running a transaction by hand and I realized that we hadn’t actually explained it anywhere. So here we are.
When you’re running a transaction by hand you’re doing everything your mailserver would do to deliver an email, but you’re doing it yourself. That means that you get to see all the responses from the mailserver you’re sending the mail to, and also any delays or errors in much more detail than you can usually get from mailserver delivery logs.
I want to send some email to playingwithtelnet@gmail.com. There are two main steps to doing this – first I need to find out which mailserver I need to talk to to send mail to gmail, then I need to actually send the mail.
To find the mailserver I have to look up the MX record for gmail.com. From a unix / linux / mac command prompt you can do that like this (the bits you type are in orange):