Spam emails can be blocked at server level

if you have your own domain and hosting.

Unfortunately, rigourous spam control software is sometimes a bit too effective and will get rid of perfectly legitimate emails along with the baddies.That is because on large email providers, so many people share the same servers, and a few bad spammers can cause a server to be listed in an RBL as a bad IP. Normal private people end up being blocked along with the rest.

Some email clients can be ‘taught’ by the user to know what is spam and what is not. That’s all well and good, but if the program submits the information to spam lists, legitimate senders can end up being condemned (along with people who use the same ips). Many users mark emails they requested or from online shops as spam when they should simply unsubcribe. That is simply not fair, but the general public don’t care and don’t bother to remove themselves properly.

RBL stands for Real-time Blackhole List

A Domain Name System-based Blackhole List, Domain Name System Blacklist (DNSBL)
or Real-time Blackhole List (RBL) is a service where with a simple DNS query mail servers can check whether a sending IP address is on a blacklist of IP addresses reputed to send email spam.
Most mail server software can be configured to check one or more of such lists – typically rejecting or flagging messages if it is from a listed site.

(REF. https://en.wikipedia.org/wiki/Domain_Name_System-based_Blackhole_List)

Many mail servers IPs belonging to btinternet.com are in an RBL
The same goes for gmail.com and other large email providers.
Neither our host nor I have control over blacklists and your host can’t guarantee anything will be sent or received.

INCOMING EMAILS

You might not be receiving all the emails sent to you. They may be bounced and the sender notified or even deleted without any notification. RBL rejections are because the email providers’ mail systems do send a lot of spam and there are thousands of spammers using the same mail ips.

A mail server will usually send everything it receives, whether direct or forwarded mail.
They may have filters both for sending and for receiving email, and the spam filters are responsible for stopping spam.

Your host may have filters that cannot be removed so that the server is protected from large scale attack. Spam filters are complex and take many factors into account.

I Ran some TESTS for BT by sending emails from a BT account to my domain email. I have not done any for gmail.

Tracing failures

I was able to see the actions taken by logging in to the hosting control panel (cPanel) and tracking recent failed emails. The system only keeps the record for a short time, so you can’t see historic failures.
When I changed the email client settings to include the ‘reply to’ header, the email delivery succeeded, but by then the sending server had changed so although having the ‘reply to‘ is good practice and will help all email types with deliverability, it cannot be proved that the added header made the difference in this case.

One of the common and effective filters is one which checks the RBL for black-listed Ips.

e.g.
This header was rejected and returned the email to the sender.

JunkMail rejected – mailomta26-sa.btinternet.com (sa-prd-fep-046.btinternet.com) [213.120.69.32]:64420 is in an RBL:

This header succeeded.

Received: from mailomta5-re.btinternet.com ([213.120.69.98]:14740 helo=re-prd-fep-045.btinternet.com)

BT (and the other providers) use shared SMTP servers that are used by others – and somebody has done something to get it into a blacklist.

Other Rejections

Another email was rejected with this different error:

ECDHE-RSA-AES256-GCM-SHA384:256 CV=yes: SMTP error from remote mail server after end of data: 554 5.7.1 [CS01] Message rejected due to local policy.

Please visit https://support.apple.com/en-us/HT204137

Also read https://developers.google.com/gmail/api/support

How to solve this.

I was met with ‘This question is beyond the scope of the google help community.’

Perhaps it’s also beyond the scope of this article as I could find no further public useful information about this error/failure. However, I do know that whitelisting people or organisations you WANT emails from is often the solution.
You can do several things that may solve the problem:

• Whitelist the domain of online shops and online newsletters to which you subscribe.
• Add friends to your address book.
• Check that your email program has not blacklisted the sender.

If that doesn’t work, something else is stopping the emails from arriving in your inbox.
Message rejected due to local policy means that the receiving server has rules in place and the person receiving the email has to communicate with their own provider to find a solution.
Good luck telling a customer they have to do that!

Artists With Websites.

When you provide a way for people to sign up to a newsletter on your website, be sure to redirect them to a page that asks them to whitelist your email address! Not everyone will do it, and you will lose some, but it will reduce the failures. This leads neatly to the next subject.

OUTGOING EMAILS

It also happens the other way round so care must be taken to avoid your own domain being listed on any RBL.

Sometimes the sender gets this from their own provider:

We will be unable to deliver email due to the volume of email being sent from this IP address.

This refers to the ip address relating to the device the person uses – or their internet provider’s IP, which may well be dynamic (change frequently).

Using your own domain for your email address is good and professional but it’s important that your own emails do not have the same delivery problems and that you protect it from misuse.
Using your own email address to send lots of emails quickly or to long lists of emails is a bad idea, and a mailing service should be used instead.
Mailing Services are set up to to deliver you email safely while using your domain address as the sender and for replies.

You will find a list of Services on this page: –

AutoResponder Services – List

Whether your email is hosted on your own domain or a provider such as Gmail or Hotmail, email deliverability is the primary GOOD REASON TO USE A MAILING SERVICE to send out emails to lists of members and subscribers.