To add support for updating LDAP do the following - I presume your a located in the top folder of claws-mail-2.8.1 or claws-mail-cvs:
1a. Apply the patch claws-2.8.1-add-support-for-ldap-update.patch (patch -p1 < claws-2.8.1-add-support-for-ldap-update.patch) to claws-mail-2.8.1 DO NOT USE THE VERSION FROM CVS
1b. Apply the patch ldap-update-support-CVS-rev2.patch (cd src, patch -p0 < ldap-update-support-CVS-rev2.patch)
2. Run either autoreconf -f or autogen.sh
3. run configure, make, make install
4. Install OpenLDAP
5. Use my slapd.conf for configuration
6. Use my structure.ldif as input to ldapadd to create basic structure
7. Start claws-mail and let the fun begin:-)

The prefered, and recommended, way is to coose step 1b.

Configuration in Claws-Mail:
Search Base: ou=contacts,cn=MyUser,ou=people,dc=foo,dc=bar
Bind DN: cn=MyUser,ou=people,dc=foo,dc=bar

Happy hacking
Michael <mir at datanom dot net>