Required software development freelancer for Regular Expression in Exchange 2010 job

We need to create a transport rule that would block any FROM address that starts with the following:
=?UTF-8?

All we need is the correct regular expression. We are not sure if quotes are required, or if we need to put (escape) character before the ? mark. All we do know is that it would start with ^ since we are matching the pattern at the beginning of the string.

Skills & Expertise Required

software development