Zimbra Tips: Problem Receiving from Email Client

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A few days ago, our clients asked us why they can’t receive or download emails from email clients. Mostly when using Microsoft Outlook. The error when do send/receive is “The connection to the server was interrupted”

error when receiving email

This error usually caused by

1. Wrong host or wrong upstream if you are using Zimbra Multi Server
2. You see this error on nginx.log “An error occurred in mail zmauth”
3. Cache on Memcache. So that you cannot receiving or download emails from email clients

What we do for troubleshooting are

1. Purge cache on memcache with below command

Run as Zimbra user

/opt/zimbra/libexec/zmproxypurge -a email-account

change email-account with problem account

2. If no 1 can’t solve your problem, please try direct access to IMAP/POP with port 7993/7995

If you have another solution, please comment below 🙂

Good luck 🙂


  1. Hi there i tried both ways but it keeps staying synchronizing any ideas how to troubleshoot the issue?

    Thank you

  2. Hi Iman,

    Have you ever tried changing SMTP/POP3 hostname in zimbra servers like pop.domainname.com/smtp.domainname.com. was searching for doc for this. please share if you have any


  3. This works for me, but I’m trying to get at the route of the cause. Any idea what causes this?

    Why does purging the memcached fix it? What wrong information is being stored there that causes a login to fail? I think memcached stores routing information – so is the stored routing information wrong? Is this related specifically to Outlook?


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