Deliverability issues to customers using BT internet email address

[AnnabelN]

Hi.

We send customers transactional emails to inform them when products have been dispatched and when results are available. We do not send "bulk" marketing emails. We use Mandrill for this purpose. We already use DMARC and are fully compliant. 

We've noticed that the btinternet.com domain has started to reject our transactional emails as spam. This started on June 22nd. You can see from the data that our emails began to be marked as spam from that time.

We're not sure why our emails are suddenly being blocked but would be grateful for your help in resolving. This is causing significant problems for our clients using your email domain.

We have emailed postmaster@btinternet.com but we do not have a reply yet. Please can you help? Thanks.

[DanielS]

Hi @AnnabelN,

Thanks for reaching out to us. I am sorry that you're experience deliverability issues.

Can you check our best practices for postmasters and senders of email? Are you following all of our requirements specifically making sure that the domain has a Sender Policy Framework IE SPF record?

What date and time did you contact the Postmaster address?

Thanks
DanielS

[AnnabelN]

Hi Daniel,

Thanks for replying. Yes our tech team have reviewed these best practices and couldn't find any changes for us to make so we emailed the postmaster and I have followed up here. We use DMARC / DKIM / SPF and have not previously had any issues. What is odd is that it only started on June 22nd after more than two years of successfully sending emails to btinternet addresses. Could your algorithms have changed?

We sent an email on Weds 6th July at 13:25 BST and then followed up with another at 13:32 BST that included an example of a response from your mail server to one of our emails that was rejected as spam. Our email to the postmaster includes our sender address (it is the same no-reply address for all our transactional emails).

Many thanks for your help,

Annabel.