ns4.pge.com has no MX records.
Question and response
Question
dig ns4.pge.com. MX
Answer
The response has no answer records.
Authority
pge.com. 900 SOA ns0.pge.com. ibadmin.pge.com. 93489 3600 300 1814400 900
Additional
. 0 OPT ; payload 4096, xrcode 0, version 0, flags 0