I don’t understand why this was being closed as not being a bug, but that’s probably just me… 
API not sending emails to existing contacts · Issue #14957 · mautic/mautic
This used to work fine with older Mautic installation but doesn’t work correct with Mautic 6.0.0 anymore:
Mautic Series
6.0.x series
Mautic installed version
6.0.0
Way of installing
I downloaded a release from https://www.mautic.org/mautic-releases
PHP version
8.2.21
What browsers are you seeing the problem on?
No response
What happened?
We are using the Mautic API to send emails to our users.
One of the emails we send is when a user account is being created, the user should get 2 emails, 1 with their username + instructions and 1 with their password.
In our script we check if a contact with that email exists.
NO: → Create a new contact, send the email(s), delete the contact
YES: - >Send the email(s)
The issue we’re running into now:
Keeping the new user account above as an example (should get 2 emails).
Contact does NOT exist within Mautic
- Contact is being created by our script (works fine)
- First email with username and instructions is being sent (works fine and also see it in Reports)
- Second email with password is being sent (this does NOT work, also do not see the email in Reports)
- Contact is being deleted by our script (works fine)
Contact DOES exist within Mautic
- First email with username and instructions is being sent (this does NOT work, also do not see the email in Reports)
- Second email with password is being sent (this does NOT work, also do not see the email in Reports)
We had an older instance of Mautic (version 4.4.7) and it was working fine there.
How can we reproduce this issue?
Step 1: Sent an email through the API using an existing contact