UNIX for Dummies Questions & Answers

No. You don't need a relay server to send mail directly to an MX record.

In other words, you don't need sendmail, postfix or exchange, etc to send mail. You need these to receive.

The SMTP protocol does not mandate a relay (you need an MTA).

MUA ----> MTA (The MTA is the MX record of the receiver ....)

The unix/linux mail command is a perfect example of this. PHP also has a built in mail function, etc.

Edit: I don't think the MTA MX is necessarily called a "relay" ... but I would have to check, since it has been a while.

Ah cool, I did not know that. Learn something new every day!

Generally, I call a "relay" an intermediate MTA between the sender and the receiving MTA; but I would need to check terminology.

In this case, the sender can send directly to the receivers MX host. The sender does not require an intermediate relay, but many clients do, like certain web forms, etc.

On the other hand, running something like sendmail locally can provide benefits.
Well, it has been a while since I was up to speed on all the terms of SMTP MTAs and MUAs.

I hope my memory does not fail Me!!

Thanks to all for shedding light on the topic .

will definitely post after we decide the methodology to be followed

FYI, if you use PHP and add a little bit of HTML and a web server, you can make the entire code remotely configurable from the web