zmcontrol -v
Release 7.2.0_GA_2669.RHEL6_64_20120410002025 CentOS6_64 FOSS edition

I have a weird issue on my zimbra server. I have a setup with multiple backend servers and a seperate proxy and LDAP master. For 2 years everything has been working fine, but lately I've noticed some users having issues with spell check in zimbra web. I am having a hard time pinning down the problem. The users affected seem to be a random collection from different servers and different domains. So for example user@example.com can spell check, but user2@example.com can not spell check even though they are on the same backend server and in the same domain/COS

If anyone has any ideas where i need to look to troubleshoot this issue, that would be great.

Let me know if you need anymore information from my side.
Thanks