Emails from a specific sender not arriving in inbox

[Trieshard]

Emails that I know were sent by a known sender do not reach my Talktalk webmail inbox. They are not going into Junk or Spam either. It seems that they don't get past the Talktalk server. If the same sender sends it to my Gmail account they do arrive. Has anyone got any clues please?

[Gondola]

No rules is good as that means nothing is stopping mail from arriving in your Inbox.

In turn this means that either CloudMark is network blocking the sending IP address because of poor reputation and spam sending and/or Mailgun has got your email address on a suppression list possibly for the very reason that CloudMark deferred or blocked delivery.

Good that you reported the issue back to the originator. Both issues are under their control.

1. Improve the sender reputation and request de-listing from the blocklist
2. Request removal of your email address from the Mailgun suppression list

Removal from the blocklist will mean that CloudMark will see the sender reputation has improved.

Removal of your email address from Mailgun suppression will mean that the originator's mail will actually be sent and you'll receive messages once more.

[Trieshard]

Thank you Gondola for your message. I had already checked that there were no rules in my Talktalk Mail.

I have given your findings to the sender for them to sort out. Meanwhile I have a workaround by using my Gmail address and looking for the PIN email in the Bin. 

I had a similar problem during the Covid lockdown when we used Morrisons click & collect. Their emails stopped coming in to Talktalk mail and that was never resolved. I simply gave them my Gmail address and had no further problem.

[Gondola]

The originator uses the mailgun sending service. If mailgun cannot get mail delivered to your Inbox after retries then there's an automatic addition of your email address to the mailgun suppression list and that means mailgun will not send your address any more messages.

Understanding Mailgun Suppressions

The originating domain is on a spam blacklist.  TalkTalk use CloudMark sender intelligence to determine if sending IP addresses have been sending spam. It appears that the originating domain has a poor reputation in that regard. As for Gmail, there's copious amounts of spam directed to TalkTalk recipients from Gmail addresses.

What you can do is check you have no Rules defined in your TalkTalk Mail mailbox that might be diverting or blocking.

Select here:  Sign in to TalkTalk Mail

Enter your email address and password, select Sign in.

Check the  Inbox first and then check  Spam and  Trash folders for mail messages that may have been diverted from the Inbox. Bear in mind the spam and trash folders normally contain mail not older than 30 days.

• Select the Main settings menu cog icon      top right on the blue header
• Select All settings
• Select Mail and scroll down to Rules
  Select the chevron icon > to see all defined Rules
  If there's no rule defined, that's perfect
• To delete a Filter rule including any Auto forward
  select the X icon to the right of the rule
  The icon background will turn red  X
  
• To confirm you really want to delete this Filter rule
  Select the blue Delete button

[Trieshard]

I should have added that I didn't receive a bounceback non-delivery notification from TalkTalk when I forwarded the message from Gmail and I suspect that as the original sender message was an automatic response, they wouldn't either. I did contact them yesterday and they were not aware of any issues at their end.

[Trieshard]

The domain is @auth.appnotify.io  It is an automatic message sent with a PIN code for accessing their website.  As I said in my post, the messages do arrive when it is sent to my Gmail address.

If it is of any help, if I try forwarding the message from my Gmail account to my Talktalk account the message does not come through either. Messages from other senders do.

Thank you for looking at this.

[Gondola]

What's the sender domain please? The domain is the part of the email address after the @ symbol.

Have you contacted the originator and asked if:

1. they received a bounceback non-delivery notification from TalkTalk
   and if so what the TT three digit error code was?
2. they use a mail sending service
   and if so which one?
3. if they checked to see if your email address is placed on a suppression list?
   or a no-mail list?