AWS Port 25 restriction for SMTP email

To connect to an AWS Linux EC2, consult the following post: Installing and running eFORMz on Amazon Web Services (AWS) Linux EC2 instance

By default, Amazon Web Services (AWS) blocks outbound traffic on port 25 (SMTP) of all Amazon Elastic Compute Cloud (EC2) instances. If you’re encountering difficulty sending email over port 25 from an Amazon EC2 instance with eFORMz, fill out the Request to remove email sending limitations form. Additional steps are available from the AWS Knowledge Center:

1. Enter your email address so that AWS Support can contact you with updates about your request.
2. Provide the required information in the Use case description field:
   1. A clear and detailed use case for sending email from your EC2 instance or NAT Gateway.
   2. A statement outlining your plan for assuring that your account isn’t implicated in sending unwanted emails.
   3. The Region for your EC2 instance or NAT Gateway.
3. (Optional) Provide the AWS owned Elastic IP addresses that you use to send outbound emails as well as any reverse DNS (rDNS) records that AWS needs to associate with the Elastic IP addresses. When you send emails, it’s a best practice to set up an rDNS record to help prevent outbound emails from being flagged as spam.
   1. Make sure to link the rDNS record to your Elastic IP address using a DNS A record. For example, if mail.example.com is the rDNS record that you’re setting, be sure that you create an A record for mail.example.com that points to the Elastic IP address.
4. Choose Submit

Full article here: How do I remove the restriction on port 25 from my Amazon EC2 instance or AWS Lambda function?