Zimbra Troubleshooting: A network service error has occurred

Sometimes we face a problem with Zimbra webmail interface. If a user wants to login in his webmail it shows "A network service error has occurred". Though its a temporary problem but users became confused and starts feeling unwell about his email service.

By default Zimbra uses DoSFilter Throttling Mechanism to avoid large number of request over a short period of time. So if the Zimbra server see requests more than safe amount from an specific IP address / user that will be throttled and the user may face the mentioned error.

The attribute by which we have to add the safe IP address in Zimbra is "zimbraHttpThrottleSafeIPs". It does not have a default value, however these following IP addresses are whitelisted by default.

1) 127.0.0.1
2) ::1
3) 0:0:0:0:0:0:0:1
4) All mailboxd servers

To add more IP addresses in whitelist please do the following.

Login to Shell >> su zimbra >> zmprov mcf +zimbraHttpThrottleSafeIPs 192.168.2.1 >> zmmailboxdctl restart

Zimbra Tips and Tricks

Zimbra has became a very popular email server solution now-a-days. It has some amazing features for which an administrator cannot avoid it.

When a mail server works in a production environment it needs some tuning to serve its clients in a flawless manner. Here are some of them. The below commands fully functional with Zimbra 8.6 Version.

To check mail queue:
Option 1:
Login to Web Administration >> Monitor >> Mail Queue

Option 2:
Login to Shell >> su zimbra >> mailq


Remove all mails from mail queue:
Login to Shell >> /opt/zimbra/postfix/sbin/postsuper -d ALL


Clear / Remove all mails from a user's mailbox:
Login to Shell >> su zimbra >> zmmailbox -z -m user@yourdomain.com emptyFolder /Inbox


Set external relay MTA(Entire emails):
Login to Shell >> su zimbra >>zmprov ms mail.yourdomain.com zimbraMtaRelayHost mail.external.com:25 >> zmcontrol restart


Remove external relay MTA:
Login to Shell >> su zimbra >> zmprov mcf zimbraMtaRelayHost "" >> >> zmcontrol restart