PHP expert: OAuth2 for Gmail and Microsoft 365 (SMTP + IMAP + POP3)

Hi,

I need a real PHP expert to provide working code (proof of concept) that connects to a Gmail and Microsoft 365 mailbox to send and retrieve email.

REQUIREMENTS:

1. the script will connect to a Gmail and an Office 365 mailbox (both must be supported)
2. all connections MUST be authenticated using OAuth2 ("modern authentication")
3. it MUST support refresh tokens to automatically replace expired tokens
4. you MUST NOT use any frameworks (Laravel, Symphony, ...)
5. you MUST NOT use SDK from Google/Microsoft
6. you MAY use open-source third party libraries that are available via Composer or elsewhere
7. the code MUST be documented with comments
8. you MUST provide instructions on how to enable OAuth authentication in Google/Microsoft 365 (how to register the software, ...)
9. it MUST support PHP 5.5+

SCRIPT FUNCTIONALITY:

#1 IMAP
- connect via IMAP protocol
- authenticate via OAuth2
- show number of unread messages
- fetch unread messages

#2 POP3
- connect via POP3 protocol
- authenticate via OAuth2
- show number of messages
- fetch messages

#3 SMTP
- must use PHPMailer
- connect via SMTP protocol
- authenticate via OAuth2
- send a test messages


The script does not need any other functionality than what is listed. Our goal is to get working code that we can adjust and use in other projects.


IN YOUR BID:

1. please only bid if you have experience with OAuth2 and can get the job done
2. please specify how long it will take you
3. please read all of the above and confirm you have read and understood it
4. mention the phrase "OAuth is lovely" so I will know you have read this
5. post your final bid based on the above. No "let's chat to discuss your requirements" bids.


Thank you!