Not sure anyone reported this before in version 8.0.2 Patch 1 (open source, CentOS 6.3 64bit)

If I configure zimbraMailForwardingAddressMaxNumAddrs = 1 and zimbraMailForwardingAddressMaxLength = 4096, user still able to enter multiple email addresses if using semicolon as separator until hit zimbraMailForwardingAddressMaxLength 4096 characters.

For example,
abc@test.com;cde@test.com;ert@test2.com --> ERROR, system accept and send email to these three email, but this should not be happened.
abc@test.com,cde@test.com --> CORRECT, system reject and the result is correct because more than 1 email addresses
abc@test.com --> CORRECT, system accept and working accordingly