domain name system – Google and Outlook Blocking my Mail server IP

I have configured a Postfix mail server combining with dovecot and Squirrelmail on AWS EC2 Centos cloud. I am perfectly receiving all the emails from external accounts like outlook, gmail, and yahoo, etc. The problem I am facing is while sending an email from the configured server, whenever I send an email to gmail or outlook it responds to me with the following attached Errors:

Gmail returned Error

Outlook returned Error

At the start when I configured the email server the emails we’re sending from the configured email server but were receiving in the junk. Then suddenly a few days later, I started getting the above errors.
Below is the screenshot of my DNS Records.

DNS Records

In the above DNS records, the PTR, google site verification, and Gmail SPF was added when the emails were blocked.
I need a solution that how can I unblock the outlook and Gmail and other reputed email service providers to unblock my server’s IP.