פרילנסר /ית לתיקון BUG באתר PHP codeignitor framework

Hey,
My website is in php codeignitor framework verison 2.2.6.
Server php version is 5.6.
Few days ago our server provider went a security update, and since then the server is BLOCKING the SMTP emails that the site is sending through my Gmail account WITH "Swiftmailer" library, to our clients.
It also might have to do with that google gmail is no longer allowing "less secure app" for third party, as of May 2022. I'v also tried using "2 step verification" + app password for gmail, it also does not work.
"Swiftmail" library that I use is also out of service and in end of maintenance from On August 19, 2021.
The server blocks all remote SMTP emails – I already contacted sever support, they say they cannot remove the block by no mean, as it is security measure of them.
To my understanding after a lot of checks with server support, what I need in order to send emails successfully through the server security, is:
1. To use send the emails using API as "Amazon simple email service" (which I prefer as it is cheaper), or using Google Workspace mail, or using API of "Sendgrid" (less preferred, it is more expensive). I created accounts on both of them.
2. In addition to step 1 above, I also need to replace "Swiftmailer" library (that is currently being blocked by the server) to another library, like "Phpmailer", or "codeigniter built-in library". It should be compatible with codeignitor framework verison 2.2.6. and Server php version 5.6.
3. Alternately, I have heared that "Zohomail" allows to send the mails with gmail through security, so it might be that easiest solution. I have created Zohomail account.

I prefer that the emails will keep being sent from that email, as this is the mail address that my costumers are familiar with, and this way I will be most pleased. Alternately, and less preferable, The emails can be send from the server email and in the condition each email should also be send to my mail main email so that I will be able to see all the sent mails, as sometimes I need to prove to a costumer that a specific mail was sent to him.