After installing Symantec Mail Security for Microsoft Exchange (SMSMSE) to my Exchange 2010 environment which ensures high availability with Database Availability Group (DAG) and public folder replication, public folders no longer replicate correctly.
SMTP transport virus scanning is enabled in SMSMSE. This extra processing can cause timeouts in the public folder replication process: public folder replication on Exchange 2010 still uses SMTP rather than the methods used by DAG for mailbox databases.
Disable the "Virus scan messages during SMTP transport" option in the SMSMSE console:
Public folder replication should now complete successfully.