Training Data Werewolves

Originally published on LinkedIn

How email be difficult? 

You open port 25, send the message and voila! As I tend to say, the S in SMTP means Simple.

At the difference of the web or HTTP, where you are always in contact with the end user, with SMTP, you are not. Yes, with HTTP you have to deal with errors, encrypted connections, sessions, but you can usually follow the end user on your site. You know when a visitor comes to your site, and when he/she leaves it.

With email, the only interaction you control, is sending the email to the first receiving server. You may have temporary failures, "I'm busy, send a bit later", or permanent failures "I don't accept this email, and if you retry, I still won't accept it". You also have bounces, soft, "this email contained spam, I don't want it" or hard "there is no mailbox by that address here", in like "don't try to email this address ever again, check the spelling and how you got it". These bounces can happen synchronously while the sending server talk to the receiving server, or asynchronously by the way of a Non-Delivery-Report sent back as an email, especially when there are several mail servers or agents involved in the final delivery.

You may be lucky and be able to track if the email is "opened", because the client load the images inside the email, by the infamous "Tracking Pixel" (OR: Open Rate). Not many clients do that by default nowadays except on mobile. You can also track if the end user clicked on a link inside the email (CTR: Click Through Rate). Make sure you don't count duplicate events. For instance the OR calculates the number of email opened by the number of email delivered, not how many times an email was opened.