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