Workflow Notification Mailer-Unable to make a network connection

Workflow Notification Mailer cannot start.
Status is "System Deactivated".
Edit Workflow Mailer found "Validation error occurred. Please check indicated fields below".
Inbound EMail Account-> "Unable to make a network connection" message.
Solution:
1.Telnet mail server IP with port 25(SMTP) and 143(IMAP),found 143 port cannot use.
2.Found Exchange Server "IMAP4 service status abnormal.
3.Restart mail server , everything is ok.