"the source data is corrupted or not properly base 64 encoded"

Issue:​
Encoding error trying to import cert from Comodo to Exchange or complete a pending Cert request on exchange server 2010:
"the source data is corrupted or not properly base 64 enocded"
Resolution: Download as X509 Certificate only, Base64 encoded from Cert Enrollment email sent by Comodo server. This is the enocding that worked for Exchange