We are currently using Mendix Email Template Module for email sending. In email template configuration screen, while selecting the placeholder we can select only one entity object. But we require more than one entity, is there any way to access more than one entity in placeholder? Kindly note the entities do not have any association relation. If it is possible please share a SOP or guideline for the configuration.
You can select only one object there. However while creating placeholders you can use associations of the main entity to get the data from other entities.
Nope, it is just not built like that. If you can work with the associations, as suggested by Shreyash, you will be fine.
If not, you have several options:
Create a helper-entity, 1-* associated with each of your two entities; pass the helper-entity to your mail-template, and use the association to get the attributes in the mail; This is probably the most straightforward solution;
Prepare the data that you need in your mail in a separate helper-entity, that contains all attributes and their values for this specific email;
Replace the module with Marketplace module EmailService, where you prep the contents in the microflow itself. No hassle, no templates. In my not very objective opinion (I wrote the module), this is by far the best solution.