> Date: Thursday, October 15, 2020 18:57:29 +0000
> From: Jason Long <hack3r...@yahoo.com>
>
> If the DNS administrator give me an A record then can I sending and
> receiving emails from the Internet by the current configuration?
>
Assuming no MX, if an A-record is set up to point to a machine
(properly configured, including with postfix or some other MTA)
reachable on port 25 at the IPnumber, then it should be able to
receive mail inbound.
To be able to send mail directly to target mail servers you'll need
to be able to connect outbound on port 25. To successfully deliver
it, including to correspondents' inboxes, you'll need a matching Rdns
record as well as the following:
(this list is taken from an earlier message from Ahsan Khan
responding to one of your questions):
1. SPF
2. DKIM records
3. DMARC records
4. IP Warmup
5. Check the scores at mail-tester.com.
6. Domain reputation
There are a range of nitty things underlying all this which you will
need to read up on so that you understand how mail, DNS, etc. work.
You may be better off sending your mail outbound by way of a
smarthost at your provider.
