Papercut SMTP

Papercut SMTP is a local SMTP server for all your email testing on localhost.

Testing emails, the bane of every developer's existence! I test a lot of things that need to send emails and setting up yet another Sendgrid account for testing.. no thanks.

Luckily we have Papercut SMTP

Screenshot of Papercut with the settings dialog open and an Umbraco password reset email showing

Papercut is a lightweight, simple local SMTP server that not only lets you just send anything using localhost on port 25 (the default example for Umbraco configs as well by the way 💡).

Papercut runs at boot and uses very little memory, whenever an email is sent to it, you get a nice bubble in your tray telling you about it and it's got a built-in email reader as well so you can actually confirm what the email should approximately look like when it gets sent for real.

Emails are stored on disk as eml files:

Screenshot of Windows explorer showing a few .eml files

These files contain the raw message that was sent so you can inspect any problems using your favorite text editor.

That's it for today, happy local emailing!

Sebastiaan Janssen
Sebastiaan Janssen