We have a customer who has been sending html emails for invoices for some time in 8.1. One day they stopped sending with correctly, as in the arrived with the customer with no contents (body missing) and no pdf.

This problem persists. Sometimes they will send correctly for a day and then they stop again.

They have the message: Unable to send System e-mails. From System Setting Field is Blank! In the log regardless of success or not.

The email queue shows the email as correct, with body and pdf in the paperclip and correct in all cases and sent successfully

We tried changing the SMTP server used – this fixed the problem for a couple of emails then reverted to no contents attachments.

If they change to plain emails then they have the contents, but no pdf attachment.

Over the last 15 days – the server has been up and for 14 days the emails were stripped empty by the tie the arrived with the recipient. Yesterday a batch at 17:00 were perfect fine. Then it reverted today to stripped.

Any ideas?