Global Settings define the default global values for servers, accounts, COS, and domains. These default values and parameters apply if the values and parameters have not been explicitly defined in settings configured elsewhere.
The defaults are configured during installation. You can change the settings at any time from Global Settings. The Global Settings pages to configure include:
General information to set the global ceiling for the number of results from a GAL search, to define the default domain, and to configure the number of threads that can be used to get the content from remote data sources. See General Information for Global Settings.
Attachments to enable rules to reject messages that include attachments of a specific extension, to disable attachments from being read See Blocking Attachments to Email.
MTA to enable authentication, set maximum message size, enable or disable protocol and DNS checks, and add X-Originating-IP to message headers. See Configuring the MTA Tab for Global Settings.
IMAP to enable IMAP service. See Configuring IMAP.
POP to enable POPS3 service. See Configuring POP.
AS/AV to set anti-spam and anti-virus rules. See Anti-Spam Protection and Anti-Virus Protection.
Free/Busy Interop to set up free/busy scheduling across a mix of Zimbra servers and third party email server. See Making Free/Busy View Available.
Themes to customize the color scheme of existing themes. See How to customize themes and logos.
Advanced to configure the company name that is displayed in the prompt on the Authentication Required dialog used to log into Briefcase folders shared with external guests, and to add regular expression rules for Account Email Validation.
Retention Policy to set up a retention and deletion time threshold for items in user folders. Retention and deletion policies can be configured as a global setting or you can configure COS-level policies instead of inheriting from the global settings.
Proxy. See the Administrator Guide and the wiki page http://wiki.zimbra.com/wiki/Zimbra_Proxy_Guide for proxy information.