Consider performing a
SpamAssassin Rule: APOSTROPHE_FROM
Standard description: From address contains an apostrophe
Explanation
The apostrophe character "'" appears in the address part of the From: header.
e.g. <john.o'groats@example.com>
Further Info
The default scores for this rule can be found in the online list of tests.
Note that, while the email address specification allows for apostrophes to be included in the local-part of an address, use of apostrophes has been historically discouraged for security and interoperability reasons. As such addresses containing them use may be considered unusual.