Adding multiple elastic IP's to CENTOS server in EC2

First please read the following guideline before sending emails (if you want to use AWS SES service to send email)

https://docs.aws.amazon.com/ses/latest/dg/best-practices.html

Then to allocate 6 ips to your CentOS EC2 instance you can follow

• Create a new VPC or use an existing VPC in the AWS Management Console.
• Create 6 subnets in your VPC. You can use the same or different Availability Zones for the subnets, depending on your requirements.
• Launch an EC2 instance in one of the subnets you created. Make sure to choose a CentOS-based Amazon Machine Image (AMI) and an instance type that supports multiple network interfaces.
• After launching the instance, go to the EC2 Dashboard and click on "Network Interfaces"
• Click on "Create network interface" and configure it with the following settings: (Repeat the step for each of the 6 subnets you created earlier)

Description: A brief description for the network interface (optional) Subnet: Choose one of the subnets you created in step 2 Security groups: Select the appropriate security group for your instance Auto-assign public IP: Choose "Disable" or "Enable" based on your requirements Click on "Create" to create the network interface.

• Now, attach each network interface to your EC2 instance: "Network Interfaces" list > Attach > Choose your EC2 instance in the "Instance" field and click on "Attach"

Allocate 6 Elastic IPs in the AWS Management Console by going to the "Elastic IPs" section under the "EC2 Dashboard". Click on "Allocate new address" and then "Allocate" for each Elastic IP you need.

Associate each Elastic IP with a network interface: "Elastic IPs" > Actions > "Associate Elastic IP address" > "Network interface" "Associate"