Drupal 8.x

A bit of context before I come to the question: When we build our site with composer install, we use a proxied repository instead of using Packagist and packages.drupal.org directly. This is a recommended approach to protect against Dependency Chain Abuse (Source: OWASP - "CICD-SEC-3: Dependency Chain Abuse"). One Drupal-Module we use has specified patches for a different module and for core in its composer.json file.

Hello,

I want to get my Drupal site up to date, at least to Drupal 9.4 that still supports php 7 Drupal 9.4 dropped official support for PHP 7.3, . 

I installed some modules via UI, so also want to install them with composer now, to get it all managed by composer.

When I go to do a simple

composer update

or

My Drupal site used to send me notifications for things like new account requests. At some point this broke, perhaps when going from 7 to 8. Now I want to fix it. I can see in the recent log messages that mail was sent,  but the recipient never received it, nor did I. 

Drupal 8.6.18

PHP 8.1.16 (I think)

Do I need to install the SMTP Authentication Support module? The doc page says it requires PHPMailer 6.x. 

My site is hosted at GoDaddy. Does that rule out using composer? How do I get to a shell command line? Do I just use manual installation through cPanel?