Mailscanner is blocking SOME pdf attachments

[ttremain]

This is a message from the MailScanner E-Mail Virus Protection Service
----------------------------------------------------------------------
The original e-mail attachment "Ole Rosberg - week 5-8. Invoice_100029.pdf"
is on the list of unacceptable attachments for this site and has been
replaced by this warning message.

If you wish to receive a copy of the original attachment, please
e-mail helpdesk and include the whole of this message
in your request. Alternatively, you can call them, with
the contents of this message to hand when you call.

At Wed May 3 06:35:57 2017 the virus scanner said:
MailScanner: Blocked Filename Detected (Ole_100029.pdf)

I have explicitly allowed .pdf in the config file:
/usr/mailscanner/etc/filename.rules.conf
allow \.pdf$ - -

With no other reference to .pdf

Please advise

[sawbuck]

Likely seeing it as a double file extension.

https://support.configserver.com/knowle ... -extension

[ttremain]

Followup:
It was the double extension.