I experienced the similar problem at SMTP server and the problem has been fixed after I changed the following parameters :-
config setprop ssmtpd Instances 200
config setprop ssmtpd InstancesPerIP 50
run command : signal-event email-update
However, we are experiened another POP 3 server error as follows. Does anyone can advise solution to solve it ?
The TCP/IP connection was unexpectedly terminated by the server. (Account: 'pop.pacific.net.hkl', POP3 Serer: '219.90.114.83', Error Number: 0x800ccc0f).