Pigeonhole Sieve Vacation Reply-To peculiarity with inbound AWS-SES

jeremy ardley jeremy at ardley.org
Tue Feb 7 21:33:34 UTC 2023


On 8/2/23 05:08, Dr. Rolf Jansen wrote:
>> Am 07.02.2023 um 17:54 schrieb jeremy ardley<jeremy at ardley.org>:
>>
>> On 7/2/23 22:01, Dr. Rolf Jansen wrote:
>>> To begin with, usage of Amazons Simple Email Service (SES) is mandatory for outgoing mails from AWS-EC2 instances.
>> I run AWS-EC2 instances using postfix to send a receive mail. They can send direct assuming I set up suitable SPF, but they typically forward mail to another host under my  control that is not on AWS to use as the outgoing server.
> OK, that’s another use case. Many do use a full fledged Postfix/Dovecot installation. However the outgoing port 25 into the internet is blocked by AWS, and therefore we may either use a third party relay for our outgoing emails or may use SES, which is not that bad - except some unusual peculiarities.
>

This is off topic, but to be precise:

- AWS throttles but does not block traffic to a *destination* port 25.
- The *origin* port on the EC2 instance is an unprivilged port, not port 25
- If you use a relayhost you typically send from an unprivilged EC2 port 
to port 587 on the relay host

Jeremy
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