Try using the following for your Custom Rules to score email from the TLD's you want to block.
Not the cleanest way, but until SM builds something in its the best we could find.

Example 1: (Meant to block TLD; From *.accountant)
    Rule Source: Header
    Header: From
    Rule Type: Regular Expression
    Rule Text: .+\.accountant>$
    Weight: 20

Example 2: (Meant to block TLD, Reply-To *.accountant)
    Rule Source: Header
    Header: Reply-To
    Rule Type: Regular Expression
    Rule Text: .+\.accountant>$
    Weight: 20

Example 3: (Meant to block TLD, Return-Path *.accountant)
    Rule Source: Header
    Header: Return-Path
    Rule Type: Regular Expression
    Rule Text: .+\.accountant>$
    Weight: 20

Here's a list of the TLDs we are blocking.  Note the format:
DOT  PLUSSIGN  BACKSLASH   DOT DOMAINTLD  GREATERTHAN DOLLARSIGN
.+\.accountant>$
.+\.bid>$
.+\.br>$
.+\.cf>$
.+\.click>$
.+\.club>$
.+\.cricket>$
.+\.date>$
.+\.download>$
.+\.eu>$
.+\.faith>$
.+\.fr>$
.+\.ga>$
.+\.gq>$
.+\.in>$
.+\.link>$
.+\.lol>$
.+\.ml>$
.+\.ninja>$
.+\.party>$
.+\.pw>$
.+\.racing>$
.+\.review>$
.+\.rocks>$
.+\.rs>$
.+\.science>$
.+\.space>$
.+\.tk>$
.+\.top>$
.+\.tr>$
.+\.trade>$
.+\.wang>$
.+\.webcam>$
.+\.website>$
.+\.win>$
.+\.work>$
.+\.xyz>$