Background: We're working on a dashboard like email report. It has a lot of charts in it that are rendered as inline images to the email in MHTML format. This report has a parameter option to select what line of business to run it for, and we set up a subscription for each option.
Problem: in Outlook and an iPhone based email client (not sure which one): if the user quickly flips from an unrelated email, to one subscription email to another subscription email, chart images from the first subscription email are present in the second.
Possible cause: SSRS / Power BI Report Server uses the same attachment filename for the inline images between emails. When Outlook is starting to render one email for preview and switches to another, the attachments from the first email are preserved in cache and not reloaded.
Suggested solution: I looked at some email notifications from another system software we use. That software places a GUID into the filename of image attachments, making them unique between emails.
