Re: Email direct from IBM i without relay (was: New lower cost IBMi announced)

Actually the email client normally connects to a mail router (which can be
an in house exchange server, a cloud based server like gmail or office365,
your ISP's mail router, etc) and drops the mail off there. Then the mail
router delivers to the final recipient (at example.com).

Okay, but we're not talking about PC email clients (i.e. Outlook), we're
talking about sending email from IBM i.

In 99.9% of the cases, this is how it works with PC clients or clients such
as SNDDST, MSF, MAILTOOL, ESEND, etc.

Again, we're not talking about sending email from PC clients.

I'll leave it to you and Richard to explain how MAILTOOL and ESEND works.
But SNDDST and MSF use the IBM i SMTP client to connect send email directly
to recipients, without the help of a relay service.

I won't get into why (except reverse DNS being one) but rarely if ever
should email be delivered directly from the client to the recipient.

I don't understand your point regarding reverse DNS, but I do understand
that you "won't get into why".

Port 25 is only for non-secure connections. 465, 587 and others are used
for SSL/TLS. When connecting to a mail router that requires that type of
authentication.

In regard to port 25 being used for non-secure communications, SMTP is not
a secure protocol. My understanding is that some server along the chain
will eventually connect to the SMTP server on port 25 at the final endpoint
to deliver the message.

That brings us back to the question, why use intermediaries such as relays?