So here's an odd one. And worse, it appears to be affecting some users but not all.

One of my admins said to me:

QuoteI had a member pm me this evening who has been trying to contact (via a pm on the forum) another member since last Wednesday. Whilst I correctly got notification of his message when I logged onto the forum this evening, in the past I have always received an email notifying me that a message is "waiting" for me - I didn't get this (and thinking on it, I used to get email notifications of new members joining - but I no longer get those either.

Have you turned off the email notification service?

Obviously I hadn't so I asked him more questions and he responded.

QuoteI haven't changed my profile, also in having checked it, everything is set correctly. It all used to work, but for some time now I've not received ANY email messages, be they from PM's or notifications of new members joining.

I suspect others experiencing this issue haven't changed anything either.

Browser cache etc you mention I clear down regularly, virtually every day.

I agree that there shouldn't be any difference, but why it works for some and not others I have no idea.

SO I know of one admin for whom it is working fine (locate in NZ) one for whom it isn't (located in UK) and various members in UK for who it isn't working.

I'm at a loss

Does anyone have suggestions as to how I might diagnose and fix this please?

SMF 2.0.19
Haven't made any changes recently at all - not to PHP or database or mods or permissions or anything.

Did you move servers?
Is it only one email provider that is affected or are they all different?

I have heard of this in 2.1 but not so much in 2.0.19.  I'll see what I can find.

It appears that it is server related and adjustments have been made and should be working now.

Well that didn't work but I have another thing to try.

The email logs will tell you why an email has been rejected. It can be a few things, SPF record, DMARC record, reverse DNS record, and your server IP on a blacklist.

Try running your domain at this site https://mxtoolbox.com/emailhealth it might point you in the correct direction.

DMARC apparently.

Whatever that means.

Any simpler English translation for this:

QuoteWhat you see when your domain has this problem
   DMARC Record Published Failed   Details area   Ignore
Monitor, detect and fix real world problems with your SPF and DKIM configuration
More Information About Dmarc Record Published
If you are encountering this error of No DMARC Record found, this means that your domain does not have a published DMARC record. DMARC Records are published via DNS as a text(TXT) record. They will let receiving servers know what they should do with non-aligned email received from your domain.
Domain-based Message Authentication, Reporting, and Conformance (DMARC) is a mechanism for improving mail handling by mail-receiving organizations. The ultimate purpose of DMARC, according to RFC-7489 is to provide a "mechanism by which email operators leverage existing authentication and policy advertisement technologies to enable both message-stream feedback and enforcement of policies against unauthenticated email. Email originating organizations utilize DMARC in order to express domain-level distribution policies/preferences for message validation, disposition, and reporting.

How DMARC Works:
 
DMARC adoption has risen dramatically and has a positive or negative impact on your email deliverability. All of the major email providers support DMARC. By some measures, 80% of mailboxes worldwide are protected by DMARC.

DMARC dramatically improves on SPF and DKIM by letting you:

Monitor, detect and fix real world problems with your SPF and DKIM configuration
See the email volumes you're delivering to inboxes
Identify threat emails pretending to come your domain. (Spoofing)
Control the delivery of your email and defend against spoofing attacks.
 

How do I set it up?
 
It only takes a few minutes to get started with DMARC and you'll see immediate benefits. The first thing you need to do is add a simple DNS record to enable DMARC reporting. If you would like MxToolBox to handle your DMARC reporting for you, just add this simple text (TXT) record to your domain's DNS.


What is DMARC Authentication?
 
To pass DMARC authentication, a message must both Pass and Align for either SPF or DKIM. Even if a message passed authentication for both SPF and DKIM, it could still fail DMARC authentication if one of them does not "align." There are two ways to pass DMARC authentication:

SPF Passes, meaning the message was delivered from an IP address published in the SPF policy of the the SMTP envelope "mail from:" (mfrom) domain, and also

SPF Aligns, meaning the <From:> header visible to the end user matches the domain used to authenticate SPF. (e.g. the envelope "mail from:" domain)

-OR-

DKIM Passes, meaning the message was correctly signed by the d= domain in the DKIM header, and also

DKIM Aligns, meaning the <From:> header visible to the end user matches the d= domain in the DKIM header.

What is alignment again?
 
When a message is aligned, the end user recipient knows who really sent the message.

SPF and DKIM are only authentication mechanisms. Passing SPF or DKIM authentication only means the receiving organization can identify the real sending domain. But typically, the end user receiving the message never sees this domain. Instead, they see the "From:" address in the email header.

So it's possible for a message to pass both SPF and DKIM authentication, but still trick the end user to thinking it came from someone else (i.e. spoofing). When a message is aligned, the friendly domain visible in the email client matches the domain used to authenticate with SPF or DKIM.

What DMARC Policy should I publish?
 
If a message fails DMARC authentication, the receiving organization should honor the "disposition" you publish in your DMARC policy. This is the p= value in your DMARC record:
 

p=none   Take no action other than sending aggregate reports. This let's you see which messages are failing DMARC and fix the problems. With reporting enabled, you will get reports from organizations all over the world, including all of the big mail providers like Google, Yahoo, and Hotmail.
p=quarantine   Once your DMARC compliance is high enough, you may direct receiving organizations mark messages failing DMARC as spam. You're telling the world your SPF and DKIM deployment is very accurate and to be careful with any message that fail.
p=reject   Once you're sure all of your important messages are passing DMARC, you may direct organizations to outright reject messages that fail. You're telling the world your SPF and DKIM deployment is fully complete and up to date.
 

DMARC is the key to improving Email Deliverability!
Email is the key to your customer communication strategy. But, what is your email reputation?

Setting up and managing your DMARC configuration is the key to getting insight into your email delivery. MxToolbox is the key to understanding DMARC.

MxToolbox Delivery Center gives you:
Who is sending phishing email purporting to be from your domain
What is the reputation of your domains and delegated IPs
Where other senders are and What their reputations are
How your SPF, DKIM and DMARC setup is performing
What on-going maintenance you need to maintain and improve your email deliverability
 

I think only the host can set a DMARC record.
A better explanation https://dmarc.org/wiki/FAQ#How_does_DMARC_work.2C_briefly.2C_and_in_non-technical_terms.3F

This might still not fix your issue, are you able to look at email logs? The receiving server will tell the sender why the email was blocked.

Try using these tools from the same site:

https://mxtoolbox.com/dmarc/dmarc-email-tools?referrer=cms_dmarchome

Thanks I'll look into it.

@LandyVlad  I just took a look at it.  Your SMTP setting is wrong, it looks like it's got all your mail server info pasted into it.

Quote from: lurkalot on Oct 21, 2022, 03:25 PM@LandyVlad  I just took a look at it.  Your SMTP setting is wrong, it looks like it's got all your mail server info pasted into it.

Thanks mate - I'll check my hosting and find the server details.

OK so finally getting back to this - have posted on the smf forum but will duplicate here the detail:

My forum isn't sending out notifications, but used to do so.

It is almost certainly related to a change in host.

After speaking with my host they told me to update the SMTP credentials to those of a working email address set up inside cPanel.  (And address I already have but obviously the server will have changed from my old host) and I neglected to update it.

The SMTP credentials they confirmed:
Mail type SMTP
SMTP server
SMTP port
SMTP username
SMTP password  

so that's what I have in Admin > Maintenance > Mail > Settings

BUT it no worky.

It occurs to me that at some point (I can't recall when exactly) I switched from PHP to SMTP in the mail settings. That may or may not have been at the same time as changing hosts, but I don't think so.  It certainly may be relevant though so I figured I'd better mention it.



Suggestions welcome.

The most obvious suggestion would be for you to immediately remove your SMTP credentials!!! ...Before you get hacked, spammed, brute force attacked, etc...

NEVER, NEVER, NEVER, openly post usernames, passwords, ports, etc.!!! This is a public board you are posting in...not a private one.

Info in that post has been edited out for security reasons.