Apple has released Mac OS X Server 10.1.3. The update is a 3.5MB file and is available in English, French, German and Japanese.
Apple says the update delivers “new functionality and improved reliability and performance.” Enhancements include: new Mail server SMTP relay restriction options; improved reliability and performance of the Apple file services, the Apache Web server, mail services, under heavy loads; security fixes for FTP and the BSD Line Printer Daemon; improved server administration of the SMB, printer sharing, WINS registration, and System Clock accuracy.
Configuration information related to Apple Mail Server SMTP relay restrictions is available at the Apple Knowledge Base.