Amazon Ec2 Mail Limit Reached While Using External Smtp Server to Send Emails

Why does Amazon EC2 limit port 25?

To be clear on SES sending limits, you have to understand there are two types of limits: Maximum Send Rate and Sending Quota

Apart from these limits, port 25 sending rate is throttled by default - but that throttle can be removed.

Maximum Send Rate

The maximum number of emails that Amazon SES can accept from your account per second.

Sending Quotas

The maximum number of emails that you can send in a 24-hour period. All new SES accounts are setup in a sandbox, and have a default Sending quota of 200 emails per 24-hour period. You can request this limit be raised, based on your needs and actual usage patterns.

To answer your questions directly:

Why doesn't it throttle ports 465 and 587?

Default rate limits are enforced on port 25, as this is the common sending port. This leads to a lot of spam being sent on this port. To prevent this, AWS EC2 throttles port 25 by default. Ports 465 and 587 are less well known, and are not as subject to as much spam abuse.

Why doesn't everyone use these ports instead of 25 and avoid the throttling issue altogether?

They can/should if their software allows use of those ports. Some legacy applications can only used port 25. In those cases, you can request the throttle be removed.

In summary regarding SES sending limits:

Ports TCP/465 and TCP/587 are not throttled
Port 25 is throttled by default, but it can be removed by request.
The Per Day Sending Quotas limits of your SES account always apply
The Per Second Maximum Send Rate limits of your SES account always apply

Amazon ec2 ubuntu and issue to connect in a remote smtp

configserv & Firewall Security Council is ;

After logging in to your WHM panel , click on the left menu configserv Security & Firewall , Firewall Configuration button , click on the resulting page . by SMTP_BLOCK title in front of one (1) i 0 (zero) at the bottom of the page by changing the update ( save, change) click the button . After this process, you must restart CSF Firewall. You can try again to send e-mail after the restart CSF Firewall plug-in.

is not already installed ;

You enterla type the following line at the command prompt after connecting to your server ssh . You can then try to send mail .
service iptables stop

Send-only Email Server

I definitely advise you to use Amazon SES. You will use Amazon's infrastructure to send emails as a service.

To me, it seems to be the best solution to your use case. You won't pay much, won't need to worry about downtime or scalability, and will simply need to use their SDK in whichever language you prefer.

Take a look at the pricing, it is quite attractive.

EC2 Scalable environment sending mail from instances

I sent request to Amazon. They have removed the limit.

How to View SMTP Server Logs on AWS EC2 Linux Apache Instance?

If your application is using your localhost as SMTP server, your logs should be in /var/log/maillog.

Note: There is a limitation from AWS for emails sent from EC2 instances:

AWS EC2 email sending limit when using third party smtp server

Amazon EC2 mail limit reached while using external smtp server to send emails