How to organize automatic sending of messages on a website with captcha?

Question

PHP

Good afternoon, I need to write a small mailing list of messages. I’ll warn you right away, this is not spam, because then I communicate with each person. It's just that the first message is always the same and is sent to random people who are online. It is necessary to send for example 50 messages in 2 hours.
I have experience with php and javascript but have never done a similar task.
It turns out that I need:
1. The script is authorized on the site.
2. Finds 50 people online.
3. Sends them letters according to the template (somewhere after the 20th you need to start entering the verification code), allows me to enter only codes in a row.
Could you tell me, please, where can I see how something like this is implemented? I just do not quite imagine the moment of authorization, for example.

Answer 1

1) This is pure spam.
2) You can look at php towards CURL.

Answer 2

there are certainly manners for spamming :) you can automate the input of special captchas. services (Google capcha solver service), there is api, for 50 captchas I think you will not have to pay so much if you really need