Email Notification Setup

Dallinger can be configured to send email messages when errors occur during a running experiment. If this configuration is skipped, messages which would otherwise be emailed will be written to the experiment logs instead.


Sending email from Dallinger requires 5 configuration settings, described in turn below. Like all configuration settings, they can be set up in either .dallingerconfig in your home directory, or in config.txt in the root directory of your experiment.

The Config Settings


The hostname and port of the SMTP (outgoing email) server through which all email will be sent. This defaults to, the Google SMTP server. If you want to send email from a Gmail address, or a custom domain set up to use Gmail for email, this default setting is what you want.


The username with which to log into the SMTP server, which will very likely be an email address (if you are using a Gmail address to send email, you will use that address for this value).


The password associated with the smtp_username.

NOTE If you are using two-factor authentication, see Two-Factor Authentication, below.


The email address to be used as the “from” address outgoing email notifications. For Gmail accounts, this address is likely to be overwritten by the Google SMTP server. See Gmail “From” address rewriting below.


Also an email address, and used in two ways:

  1. It serves as the recipient address for outgoing notifications

  2. It is displayed to experiment participants on the error page, so that they can make inquiries about compensation

Pitfalls and Solutions

A few other things which may get in the way of sending email successfully, or cause things to behave differently than expected:

Two-Factor Authentication

Having two-factor authentication enabled for the outgoing email account will prevent Dallinger from sending email without some additional steps. Detailed instructions are provided for Gmail, below. Other email services which support two-factor authentication may provide equivalent solutions.

Working with Google/Gmail Two-factor Authentication

If you are using Gmail with two-factor authentication, we recommend that you set up an application-specific password (what Google short-hands as “App password”) specifically for Dallinger. You can set one up following these instructions (adapted from here):

  1. Log into your Gmail web interface as usual, using two-factor authentication if necessary.

  2. Click your name or photo near your Gmail inbox’s top right corner.

  3. Follow the Google Account link in the drop-down/overlay that appears.

  4. Click Signing in to Google in the Sign-in & security section.

  5. Under the Password & sign-in method section, click App passwords. (If prompted for your Gmail password, enter it and click Next.)

  6. Select Other (custom name) in the Select app drop-down menu. Enter Dallinger outgoing mail or another descriptive name so you’ll recognize what it’s for when you view these settings in the future.

  7. Click Generate.

  8. Find and immediately copy the password under Your app passwords. Type or paste the password into the .dallingerconfig file in your home directory. You will not be able to view the password again, so if you miss it, you’ll need to delete the one you just created and create a new one.

  9. Click Done.


When developing locally, antivirus or firewall software may prevent outgoing email from being sent, and cause Dallinger to raise a socket.timeout error. Temporarily disabling these tools is the easiest workaround.

Google “Less secure apps”

If you do not have two-factor authentication enabled, Gmail may require that you enable “less secure apps” in order to send email from Dallinger. You will likely know you are encountering this problem because you will receive warning email messages from Google regarding “blocked sign-in attempts”. To enable this, sign into Gmail, go to the Less secure apps section under Google Account, and turn on Allow less secure apps.

Gmail “From” address rewriting

Google automatically rewrites the From line of any email you send via its SMTP server to the default Send mail as address in your Gmail or Google Apps email account setting. This will result in the dallinger_email_address value being ignored, and the smtp_username appearing in the “From” header instead. A possible workaround: in your Google email under Settings, go to the Accounts tab/section and make “default” an account other than your Gmail/Google Apps account. This will cause Google’s SMTP server to re-write the From field with this address instead.

Debug Mode

Email notifications are never sent when Dallinger is running in “debug” mode. The text of messages which would have been emailed will appear in the logging output instead.