This solution is compatible with B4A, B4J and B4i. Up until now there were two ways to send emails: 1. Using the default mobile app which required the user to actually send the message (available in B4A and B4i). 2. Using SMTP from the Net library. This required the user to enter the email...
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I want to send many emails at once, is it possible with Gmail REST API?
The simple way is to address the users email addresses into the bcc input field. Email providers will detect the (nearly) the same email content to different email addresses as spam and block your account. If needed you can try to use a pause after each send email request.
It is permissible to send "mass emails" (my company does it), but I'm not sure what the limits are. It also depends on what your definition of "mass" is. There will be limits for total allowed to send and total allowed to send per minute/hour.
This might get you started, and I'm sure there are other solutions in this forum that could be found with a simple search.