Time Zones in ZCS

Time Zones in Zimbra Collaboration

   KB 2072        Last updated on 2015-07-13  

(0 votes)

This page describes the relationship between the Zimbra Collaboration Suite and time zones. Different parts of ZCS read time zone information from different places, and this page explains it all.

There are three places where time zone information can be examined:

  • the COS and account object in LDAP
  • the user's PC (or mobile device)
  • the server OS

Different clients examine different settings.

Time Zone Sources

COS and Account

The COS and Account objects be can examined (e.g. for an account) by zmprov:
prompt> zmprov ga foo@company.com | grep -i timezone
zimbraPrefTimeZoneId: (GMT-06.00) Central Time (US & Canada)

So you can see there is a preference called zimbraPrefTimeZoneId that stores the string description of the time zone.

The server is particular about how this time zone is identified, and all settings of the attribute must match one of the "known" time zones. A list of known time zones is provided at the bottom of this page.

Note that in past versions of ZCS users may have been provisioned with the US-Pacific time zone if no other time zone was explicitly specified. If this has occurred you can broadly change all time zones (for any not set in particular) by changing zimbraPrefTimeZoneId on the user's COS. This will change the effect time zone for any user that has not had their account-specific zimbraPrefTimeZoneId set.

Changing the Timezone for the Default COS

Changing the timezone for the default COS change the timezone for all accounts unless the account has an specific timezone set. It is recommended that you do this after a new Zimbra install since by default the timezone set by Zimbra is -8 US Eastern.

To change the timezone for the COS using zmprov:
prompt> zmprov mc default zimbraPrefTimeZoneId '(GMT+10.00) Canberra / Melbourne / Sydney'

Where '(GMT+10.00) Canberra / Melbourne / Sydney' is the timezone you want to be applied.

Changing the Timezone for an Account

If you have an individual account that needs to be set to a different timezone, then this can be set.

To change the timezone for a specific account using zmprov:
prompt> zmprov ma ernie@sesamest.com zimbraPrefTimeZoneId '(GMT+10.00) Canberra / Melbourne / Sydney'

Where 'ernie@sesamest.com' is the account to be modified and '(GMT+10.00) Canberra / Melbourne / Sydney' is the timezone you want to be applied to that account.

The user's PC

This is determined by the user as appropriate for their OS.

The server OS

This is determined by the administrator as appropriate for their OS.

Example of correcting time (moving forward) and using ntpd on a RHEL5 box (as root):

Confirm timezone references are right :

zdump -v /etc/localtime | grep 2008

Install ntpd if it's not : You might need to open port access to reach outside ntp servers

yum install ntpd

Stop ntpd :

/etc/init.d/ntpd stop

Set time with :

ntpdate us.pool.ntp.org

Confirm time change :


Confirm hardware clock time :


Sync hardware clock time :

hwclock --systohc

Confirm hardware clock time :


Start ntpd now :

/etc/init.d/ntpd start

Ensure ntp running after restart :

chkconfig ntpd on

Client Behavior

There are several clients in use with Zimbra and they have different behaviors.


Different mobile clients have subtle differences in dealing with calendar time zones. Getting the time from the network can exacerbate this problem as network time sometimes includes only an offset from GMT and does not specify a full time zone definition that would include daylight savings time change over days.

There are two factors that determine the presentation of calendar data in mobilesync clients. One is the time zone setting on the mobile device, which can be either manually set or set by the network; the other is the time zone information in each meeting. This works well in most cases except for all day events downloaded to VersaMail clients (PalmOS). All day events don't have an inherent time zone, but mobilesync protocol requires a timezone setting even for these events. Zimbra server therefore uses the user account's default time zone setting when sending all day events to mobile clients. If the user account time zone happens to be different from the mobile device's time zone, VersaMail displays an all day event as two segments spanning two days.

Mobile device time zone settings impact the device only and do not alter data on the server.

The basic (or lite) web client

In 4.5.x the basic client uses the server's time zone for rendering times in message list displays. Starting in 4.5.7, the basic client uses the account's time zone setting (see bug 18033 for more info).

In 5.0.0 the basic client will use the account's time zone for message list displays and calendaring.

Note that the basic client ignores the time zone on the PC. In 5.0.0 the basic client does expose the time zone to be used; this impacts the account's zimbraPrefTimeZoneId.

The advanced (or AJAX) web client

The advanced client uses the time zone of the user's PC for rendering times in messages list displays as well as calendar functions.

Note that the advanced client ignores the time zone set on the account. As of ZCS 4.5.6 the account time zone is not exposed for editing in the advanced client.


The admin CLI zmprov provides access to the COS and account attributes and will also read them.


The Zimbra Connector for Outlook as well as "plain" Outlook using IMAP or POP will use the PC's time zone.


ZDesktop functions like the advanced/AJAX client.


iCal uses the PC's time zone.

Known Time Zones for zimbraPrefTimeZoneId

As of 4.5.0 and later releases the server understands the following time zones. Only these strings should be used to set zimbraPrefTimeZoneId.

  • (GMT-12.00) International Date Line West
  • (GMT-11.00) Midway Island / Samoa
  • (GMT-10.00) Hawaii
  • (GMT-09.00) Alaska
  • (GMT-08.00) Pacific Time (US & Canada)
  • (GMT-08.00) Tijuana / Baja California
  • (GMT-07.00) Arizona
  • (GMT-07.00) Chihuahua / La Paz / Mazatlan - New
  • (GMT-07.00) Chihuahua / La Paz / Mazatlan - Old
  • (GMT-07.00) Mountain Time (US & Canada)
  • (GMT-06.00) Central America
  • (GMT-06.00) Central Time (US & Canada)
  • (GMT-06.00) Guadalajara / Mexico City / Monterrey - New
  • (GMT-06.00) Guadalajara / Mexico City / Monterrey - Old
  • (GMT-06.00) Saskatchewan
  • (GMT-05.00) Bogota / Lima / Quito / Rio Branco
  • (GMT-05.00) Eastern Time (US & Canada)
  • (GMT-05.00) Indiana (East)
  • (GMT-04.00) Atlantic Time (Canada)
  • (GMT-04.00) Caracas / La Paz
  • (GMT-04.00) Manaus
  • (GMT-04.00) Santiago
  • (GMT-03.30) Newfoundland
  • (GMT-03.00) Brasilia
  • (GMT-03.00) Buenos Aires / Georgetown
  • (GMT-03.00) Greenland
  • (GMT-03.00) Montevideo
  • (GMT-02.00) Mid-Atlantic
  • (GMT-01.00) Azores
  • (GMT-01.00) Cape Verde Is.
  • (GMT) Casablanca / Monrovia / Reykjavik
  • (GMT) Greenwich Mean Time - Dublin / Edinburgh / Lisbon / London
  • (GMT+01.00) Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna
  • (GMT+01.00) Belgrade / Bratislava / Budapest / Ljubljana / Prague
  • (GMT+01.00) Brussels / Copenhagen / Madrid / Paris
  • (GMT+01.00) Sarajevo / Skopje / Warsaw / Zagreb
  • (GMT+01.00) West Central Africa
  • (GMT+02.00) Amman
  • (GMT+02.00) Athens / Bucharest / Istanbul
  • (GMT+02.00) Beirut
  • (GMT+02.00) Cairo
  • (GMT+02.00) Harare / Pretoria
  • (GMT+02.00) Helsinki / Kyiv / Riga / Sofia / Tallinn / Vilnius
  • (GMT+02.00) Jerusalem
  • (GMT+02.00) Minsk
  • (GMT+02.00) Windhoek
  • (GMT+03.00) Baghdad
  • (GMT+03.00) Kuwait / Riyadh
  • (GMT+03.00) Moscow / St. Petersburg / Volgograd
  • (GMT+03.00) Nairobi
  • (GMT+03.00) Tbilisi
  • (GMT+03.30) Tehran
  • (GMT+04.00) Abu Dhabi / Muscat
  • (GMT+04.00) Baku
  • (GMT+04.00) Yerevan
  • (GMT+04.30) Kabul
  • (GMT+05.00) Ekaterinburg
  • (GMT+05.00) Islamabad / Karachi / Tashkent
  • (GMT+05.30) Chennai / Kolkata / Mumbai / New Delhi
  • (GMT+05.30) Sri Jayawardenepura
  • (GMT+05.45) Kathmandu
  • (GMT+06.00) Almaty / Novosibirsk
  • (GMT+06.00) Astana / Dhaka
  • (GMT+06.30) Yangon (Rangoon)
  • (GMT+07.00) Bangkok / Hanoi / Jakarta
  • (GMT+07.00) Krasnoyarsk
  • (GMT+08.00) Beijing / Chongqing / Hong Kong / Urumqi
  • (GMT+08.00) Irkutsk / Ulaan Bataar
  • (GMT+08.00) Kuala Lumpur / Singapore
  • (GMT+08.00) Perth
  • (GMT+08.00) Taipei
  • (GMT+09.00) Osaka / Sapporo / Tokyo
  • (GMT+09.00) Seoul
  • (GMT+09.00) Yakutsk
  • (GMT+09.30) Adelaide
  • (GMT+09.30) Darwin
  • (GMT+10.00) Brisbane
  • (GMT+10.00) Canberra / Melbourne / Sydney
  • (GMT+10.00) Guam / Port Moresby
  • (GMT+10.00) Hobart
  • (GMT+10.00) Vladivostok
  • (GMT+11.00) Magadan / Solomon Is. / New Caledonia
  • (GMT+12.00) Auckland / Wellington
  • (GMT+12.00) Fiji / Kamchatka / Marshall Is.
  • (GMT+13.00) Nuku'alofa
    Verified Against: unknown Date Created: 6/27/2007
    Article ID: https://wiki.zimbra.com/index.php?title=Time_Zones_in_ZCS Date Modified: 2015-07-13

    Try Zimbra

    Try Zimbra Collaboration with a 60-day free trial.
    Get it now »

    Want to get involved?

    You can contribute in the Community, Wiki, Code, or development of Zimlets.
    Find out more. »

    Looking for a Video?

    Visit our YouTube channel to get the latest webinars, technology news, product overviews, and so much more.
    Go to the YouTube channel »

  • Jump to: navigation, search