it is quite the process to test the cbsubs mailer & due to the fact that i am doing many emails i would like a more effective process for time consumption.

AcyMailing doesn't have complex conditionals and subscription value checks to determine exactly when the email should send. It's just not comparable. A simple test email isn't going to do any good if you can't test it in the scenario it was configured for. So you need a user that meets the conditional criteria before you can test to ensure it works in those conditions. Much of the information used to check against doesn't even exist yet so a simple test isn't possible.

i can use acymailing however there is one issue that i have found with that. i want to find out if you can use the API of acymailing instead of passing the user credentials to the tables.
the reason is i have created welcome messages for all users that subscribe to this particular plan (lets call it plan x). it works great but when the user is subscribed via cbsubs they are not being sent the welcome newsletter. i have contacted acy in regards with the following response:

if they insert directly the data in the acymailing_listsub table the subscriber will be attached to the list properly but follow-up message or welcome messages won't be triggered.
If they use our API instead, that will do the job:
www.acyba.com/en/support/documentation/6...n.html#api_subscribe

If they already use our API to subscribe the user then the issue must be something else (maybe it's triggered from the back-end?).

The user needs to be subscribed to the newsletter for them to receive the newsletter. CBSubs comes with an AcyMailing integration that subscribes them to newsletters when they subscribe to the plan. The integration uses their API and not direct database queries. Please see your CBSubs documentation for CBSubs AcyMailing usage details.

i have set the content prepare content plugins to "yes" so it would trigger & hopefully execute the acymailing but no luck. can you please guide me as to this?

CBSubs does not trigger AcyMailing newsletters. You need to use AcyMailing CRON URLs to do that. CBSubs Mailer and AcyMailing are two completely separate things. Enabling content plugins just allows Joomla content plugins to act on the content (plan description for example).

the issue is the way that cbsubs is adding the users data into acy

This is completely incorrect. We are using their API exactly to their specification. You can see this in CBSubs GPL in the below file where the API is used correctly to subscribe and unsubscribe users from newsletters.

/components/com_comprofiler/plugin/user/plug_cbpaidsubscriptions/plugin/cbsubsacymailing/cbsubs.acymailing.php

As you can see in the above our usage follows exactly their usage shown in their documentation below for "Subscribe or remove a user from one or several lists".

www.acyba.com/en/support/documentation/64-acymailing-developer-documentation.html#api_subscribe

Subscribing and unsubscribing a user does not trigger a newsletter to be sent. You need to send the newsletter manually or use CRON to do it.