My application is configured to send out email notifications when an event happens. Sometimes this is fairly often (every minute), and every email has an attachment (up to 6-10 attachments), so each email can be pretty hefty, but not ridiculously so (500k per email is the maximum we would ever reach).
The problem we run into is that the emails will get delayed. They will still be delivered, but there will be a delay in there. The strange part about the delay is that it is very consistent (e.g. all emails arrive 1 hour late).
I thought this was a problem with my email server, so I moved my mail service to a (paid) virtual server with lots of memory, but that didnt seem to help (and I have plenty of resources left).
Does anyone have any insights into what might be factors here, or what kind of options do I have? Is moving to a paid SMTP service likely to solve this problem?