In 6.0 sendmail, /etc/mail/ip_allow is used to control who's allowed relaying. In 6.1 sendmail, /etc/mail/allow is used. Upgrade tries to preserve the settings from ip_allow but fails and generates an incorrect setting, breaking relaying. Example: Before upgrade, /etc/mail/ip_allow contains two lines 192.168. 10. After upgrade, /etc/mail/access contains the two lines 2 RELAY 2 RELAY This is incorrect. /etc/mail/access should contain 192.168 RELAY 10 RELAY after the upgrade.
fixed in current devel tree