Eventful Email
In Ruby - Lightning Talk

Email Processing I’ve
Seen
• Sometimes done with a catch all alias on
the mail server
• Store emails as files on disk
• Implement a file scanner to read and
process messages

Catch All Aliases?

Really?

• Catch All aliases encourage spam to your
server
• Waste resources processing mail that
should be bounced

What Else To Do?

Process Email as it
Arrives

Postfix

Event Machine SMTP

WTF
• Postfix on port 25 relaying to EM-SMTP
• Postfix receives and buffers the email
• Forwards it onto EM-SMTP when available

Setup Postfix
• Setup Basics
• http://articles.slicehost.com/email

/etc/postfix/main.cf
myhostname = mydomain.com
myorigin = /etc/mailname
relayhost =
mynetworks = 127.0.0.0/8
relay_domains = mydomain.com
transport_maps = hash:/etc/postfix/transport

/etc/mailname
mydomain.com

/etc/postfix/transport
mydomain.com smtp:[127.0.0.1]:2525

Write Your EM Server
class MySmtpServer < EM::Protocols::SmtpServer
def initialize(*args)
super
@parms[:chunksize] = 1024
end

Specify Who Can
Receive
Return True for OK
def receive_recipient(recipient)
!!User.first(:email => recipient)
end

Tell It What to Do
def receive_data_chunk(data)
# Do stuff with data
# collect it in an ivar
# collect in a file
true
end

Once The Message Is
Complete
def receive_message
# Do Stuff if you’ve collected in an ivar
# Or sent to a file
# Clear ivar
true # false rejects message
end

Fire It Up
EM.run {
EM.start_server \"0.0.0.0\", 2525, MySmtpServer
}

More Information
http://github.com/eventmachine/eventmachine
Huge Thanks to Andy from Octopus Computing
http://octopus.com.au/