Wednesday, October 3, 2018

Issue sending Email from the Ec2 instances

I configured the postfix recently on the ec2 instance and tried sending the mail with all the security group rules and NACL rules in place. However after i was initially able to telnet to the google email servers on port 25 soon i start getting logs with no connection error messages and ultimately i was not able to do telnet and even the mails were not going or received by the receiver.

This problem was only coming on the ec2 instances. This is because the Amazon throttles the traffic on the port 25 for all the Ec2 instance by default. But its possible to remove this throttling over the ec2 instance over the port 25.

For removing this limitation you need to create a DNS A record in the route53 to your instance used in the mail server such as postfix.

With the root account open the following link


And provide your use case for sending the mail. Than you need to provide any reverse DNS record which might be required by the AWS to create as the reverse dns queries are used by the mail servers to verify the authenticity of the mail servers which are sending the mail and in turn lookout for these servers as mail is received to verify they are not sending mail so a proper resolution increases the chances of the mail being delivered to the inbox rather than spam.

Once the request is approved by the AWS Support you will receive a notification from the support team that the throttle limitations has been removed on your ec2 instance and you can send the mail to any recipient basis of your use cases.


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