Email archive can create records with null XML

The Email Archive tool/service can sometimes create records with null XML in the MAILARCHIVE_MESSAGE table.

This both currently causes problems in the tool (c/f SAK-13480) and points to some other underlying problem (lost data?).

Our production db shows 76 records with null XML, as in:

select * from MAILARCHIVE_MESSAGE WHERE XML IS NULL order by MESSAGE_DATE;

dating back to 2007-05-24 and still being created in 2-5-x.