E-mails from my energy supplier bouncing back to them

[DaveB1361]

My energy supplier reports that they are unable to send an email to the registered email address they have for me from the email address of - hello@octopus.energy - and have asked is they have been blocked. Not by me! They were able to send an email from an employees account - xxxx@octoenergy.com to the same registered e-mail address which is - obscured for customer security

I do not have any rules set for handling emails.

Please can you check my email account to see if there is anything blocking their email address at the server (or wherever) or if there are any other issues eg would an webmail server outage cause a problem resulting in the sender automatically blocking a failed email - which has happened in the past to another sender.

For good measure could you also check my other e-mail accounts - and to confirm they are working correctly - I sometimes go days without getting anything on the obscured for customer security

While I normally access all 3 accounts through Thunderbird, I have checked the accounts on Web Mail to check they are the same as in the email client.
Thanks

[Gondola]

Octopus Energy must add the sending IP address to their SPF file. Then when TalkTalk's inbound mail servers carry out the same check that I did on the SPF file that will then fully authenticate the mail that will be accepted for delivery to your mailbox.

[DaveB1361]

Thanks for the reply Ady -interesting as the info I sent Gondola from an e-mail of the 4th from the same e-mail address was from a valid IP address and a permitted sender.

What happens next? Does TalkTalk add the  IP address to the list of permitted senders? Or do I need to tell Octopus Energy that there is a problem with their IP address?

[Ady-TalkTalk]

Hi DaveB1361, Octopus's sending mailbox has been blocked as spam. It looks like the IP used is not within the expected range. 

Ady

[Gondola]

Thanks Dave.

I have obscured personal data from your posts. The email checks out OK. There is an SPF file that validates the sender IP 159.183.129.74 as a permitted sender. So although it's a different mail sender to a previous investigation, this time it's perfectly good.

What I'm saying is, assuming current mail messages are identical in sending characteristics to the one you received on 4 October, there is no obvious reason for current mail messages to be bounced. i.e. they are correctly authenticated by the Octopus Energy SPF file.

Or to look at it another way, the mail message you received on 4 October came through OK because it was correctly authenticated. Current mail messages may not be correctly authenticated.

[DaveB1361]

Thank you for replying quickly Gondola. Here is the information from Viewing the source of an email received on 4th October 2023: 

Return-Path: <obscured for customer security@mail.octopus.energy>

Received: from o8.ptr6837.em5163.mail.kraken.tech ([159.183.129.74])
by mx.talktalk.net with SMTP

I'll have to ask if my contact can get the bounce back code for you. 

[Gondola]

It would be useful to know what the bounceback error code was that they received. This will include a TT three digit code. From that I can diagnose what the issue is likely to be.

Do you have any previous mail messages from hello@octoplus.energy ?

If you do it would be most useful to have a look at the email header (View source in TalkTalk Mail) and to know what the Return-Path: email address within chevron brackets is and then what the line is that starts Received: from sending address ([ IP address ]) by mx.talktalk.net with SMTP. i.e. the address within the rounded and square brackets that I'd like to see, as received by the MX server at TalkTalk - so, just the email header line that starts with Received: and ends in by mx.talktalk.net with SMTP.

The last time I investigated Octopus Energy emails their SPF file was not set up to correctly to register the mail server's sending address. Then they were using megamailservers.eu as their mail sending service.