I am running v18.104.22.168. I use AOE scheduler for my cron and SMTP pro by aschroder for my email.
When a customer places an order they get their order confirmation email. Then when their order is shipped and the shipping email is sent the order confirmation email is often resent between 1 and 4 times. This happens straight away after the shipping email is sent. Occasionally the shipping email is sent twice as well. There does not appear to be any pattern to it and it is getting worse. I did not notice it as it was only happening occasionally however looking at my email logs (from SMTP pro) it is getting worse and is now happening with every order.
This is not realted to the email problem with early 1.9 versions (New order email being sent twice) as the emails are going to the right customer and the
core_email_queue_recipients tables have no records in them.
I have also read that there are problems sending a copy of sales emails to a seperate address in v1.9 but i dont do this. I bcc them to my email address.
I have been hesitant to uninstall SMTP pro to see if that is the problem as my emails end up in spam without a smtp plugin (and i would rather my customers get multple emails than not at all) but I will try that now. I did send an email to the developer but have not heard back form him however it is a very popular plugin and if it were at fault I am sure that someone else would have encountered the problem
Anyone have any ideas as to what is causing this?