[exim] ldap returned data format

How should one deal with multi-valued attributes in ldap,
where an attribute could contain a comma?

The spec says
"If the attribute has multiple values, they are separated by commas."
Actually I see "comma, space" - but while this is less likely to
appear in an attribute value it still isn't impossible
(I want to hold regexes, among other things).

Cheers,
Jeremy