ErrorInfo: Invalid address: (From): [email protected]

Hi There!

I have a serious issue here, maybe you give me a hint.

I moved the website from CentOS to RockyLinux and everything is working properly.

I set up my host to send and receive by AWS SES with Postfix and Spamassassin, and all emails working perfectly in sending and receiving.

I have dozens of websites in subfolders NOT subdomains, So all websites are under the main domain, I have no Caching plugins.

In all sub-folders websites, WP SMTP works perfectly with the following settings:

• Mailer: Other SMTP
• SMTP Host: localhost
• Encryption: None
• SMTP Port: 25
• Auto TLS: ON
• Authentication: OFF

We made these settings because the OS itself is configured with AWS SES, So all mails are sent using the localhost settings and it works perfectly.

The Issue:

In the main domain which is Multisite, Non of sites can send the test mail.

Error Log:

Versions:
WordPress: 6.2.2
WordPress MS: Yes
PHP: 8.0.27
WP Mail SMTP: 3.8.2

Params:
Mailer: smtp
Constants: No
ErrorInfo: Invalid address: (From): [email protected]
Host: localhost
Port: 25
SMTPSecure:string(0) ""
SMTPAutoTLS:bool(true)
SMTPAuth:bool(false)

Server:
OpenSSL: OpenSSL 3.0.1 14 Dec 2021
SMTP Debug:
Invalid address: (From): [email protected]

It seems like this plugin [Restrict Usernames Emails Characters] creates a mu-plugins folder, I deactivate it and removed mu-plugins folder, but nothing.

P.S. This following option does not work, and all values in wp-options table are still there.

Uninstall WP Mail SMTP: Remove ALL WP Mail SMTP data upon plugin deletion. All settings will be unrecoverable.