At the end of each month, one of our clients sends us a bunch of emails related to invoicing (~120 emails). Each email has the same subject and body, but a different attachment.
The emails are sent to an email address which gets forwarded to a salesforce email services address as part of Email-to-Case.
After about 20 emails, cases stop being created and salesforce errors with
The following errors were encountered while processing an incoming email: LIMIT_EXCEEDED : A loop was detected in Email-to-Case processing <insert email here>
Other than asking our client to change this email, or changing process on our end, what options do I have to stop SF flagging these emails as in a loop?