Email Confirmations - some not sent/received

[zgap111]

We've had some complaints from customers not receiving the email confirmations...

We also get sent a copy from the server... and we also don't have it
- feels like either the emails were not sent
or
- something blocked them (both emails : 1 to the customer and 1 to ourselves)

Anything I should check?

I notice (so far):
#1 : Orders affected are £6000+ in value
#2 : Paid by Bank, so not via 3rd party payment
#3 : Affected orders from NIGERIA and FRANCE
#4 : Unaffected orders from UK and ITALY
#5 : I don't think it's SPAMhaus etc... as we don't get the email also
#6 : Was ok on 18th January 2021... 1st reported problem on 28th January 2021
- We updated to v18.05 in mid December 2020, so I don't think it's the software(?)
- however, I remember in the past we had a problem with Paypal timing out... could this be similar?

[Mike Hughes]

When you say "#2 : Paid by Bank, so not via 3rd party payment" what do you mean? Normally the order confirmation email is sent when the customer is returned from the PSP after paying but I'm not clear how you're processing these payments.

[Goz]

Is there any correlation between the email addresses? Are they all or mostly BT internet addresses? All my site - and many of my client's sites - often struggle getting emails to BT internet email addresses

[zgap111]

When you say "#2 : Paid by Bank, so not via 3rd party payment" what do you mean? Normally the order confirmation email is sent when the customer is returned from the PSP after paying but I'm not clear how you're processing these payments.

There was a question on time delay... so bank transfer selected ones don't have any delays

Is there any correlation between the email addresses? Are they all or mostly BT internet addresses? All my site - and many of my client's sites - often struggle getting emails to BT internet email addresses

An affected customer placed 3 orders... each with a different email address... all were affected
I've raised a ticket with the hosting company and their response is

This is being investigated currently, this is not an issue with country (as the email providers are generic, gmail + yahoo for the most part) and I dont think an issue on your end. We'll update you shortly.

[zgap111]

Hosting company sent this:

I believe this was blocked by our anti spam measures, I've made some tweaks to this so hopefully shouldn't trigger again. If you can try sending again this should hopefully be resolved fror you.

Testing now... hopefully ok.