How to change the default date format in Rules? I've created a rule to send an html email which contains a date, printed using tokens as [commerce-order:field_delivery_date]. In email, the date looks like 2016-07-08 00:00:00 to 2016-08-02 00:00:00. The date may or may not be an interval. 

How can I alter the date format in Rules?

I know that I can use something like [commerce-order:field-delivery-date:value:custom:j m] - [commerce-order:field-delivery-date:value2:custom:j m Y] which outputs 08.07 - 02.08.2016. 

But, I don't always have an interval, I can only have the start date, which should be printed as 08.07.2016.
Try to use what you have defined as the format for short / medium / long format in your Drupal date settings, using either of these tokens:


[commerce-order:field_delivery_date:value:short]
[commerce-order:field_delivery_date:value:medium]
[commerce-order:field_delivery_date:value:long]


However, since your date seems to be a data range, you may have to enable the Entity API module and its "Entity tokens" sub-module to access the date values.

Also, be aware that Entity tokens replaces underscores  (= "_") in the tokens names by dashes (= "-"), so in your case "field_delivery_date" becomes "field-delivery-date". And with that, this is how it should look like:


[commerce-order:field-delivery-date:value:short]
[commerce-order:field-delivery-date:value:medium]
[commerce-order:field-delivery-date:value:long]