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How the Solution Works with MS Exchange EWS

For users of the Email Sidebar on:


4 min read


RG Email Sidebar is designed to run concurrently with other processes engaging a mail server’s Exchange Web Services (EWS) and provides the customers with the necessary controls regulating EWS access by RG Email Sidebar.


What EWS access control tools allow:

Different deployment options

RG Email Sidebar supports Multi-Tenant, Single-Tenant, and On-Premise scenarios.

  • These scenarios imply various levels of data and configuration isolation between tenants: logical isolation for Multi-tenant instances, physical isolation for Single-tenant instances, of full customer control for On-premise deployments
  • As a best use practice, Multi-tenant deployment is recommended as the most cost-efficient one for an average customer, also providing a solid level of security. Other options should be considered if specific security requirements prohibit Multi-tenant operation in your Org


IP Address restrictions: RG Email Sidebar operates via a fixed set of IP addresses

The customers using corporate firewall IP address restrictions for Salesforce or MS Exchange servers connection need to allow-list specific IP addresses used by RG Email Sidebar.

  • Such whitelisting is complementary, it does not block any existing server traffic

  • See more details on configuring IP restrictions and the list of IP addresses used in Multi-tenant environments here

  • For Single-tenant configurations a specific list is communicated during RG Email Sidebar deployment

  • As a best practice, such configuration should be added over the current customer configuration, to prevent interfering with existing traffic


Filtering RG Email Sidebar EWS traffic RG Email Sidebar

Filtering can be configured to use a pre-set UserAgent header on every EWS call made to the customer’s MS Exchange server. Such configuration allows traffic filtering on multiple levels:

  • On MS Exchange / Office 365 side: using MS Exchange controls, as documented here

    • This configuration control allows additive listing of allow-listed applications, and if used by in a customer’s Org it may be extended to include traffic from/to RG Email Sidebar
  • By a stateful firewall which can block HTTPS traffic

    • As in the above case, a custom rule can be built based on an added UserAgent HTTP header to allow RG Email Sidebar-originated EWS traffic pass through, in addition to any other allowed traffic
  • The value of the UserAgent header for all EWS traffic can be set as requested by a customer

  • As a best practice, customers who already implemented EWS traffic filtering using one of the above approaches should consider extending their configuration to allow RG Email Sidebar EWS traffic


Allow EWS Access for a specific list of mailboxes only

In some configurations, RG Email Sidebar can use Exchange Impersonation and communicate with MS Exchange server through pre-configured Service Accounts.

  • If EWS are not used in any other way in a customer’s configuration, then only specific mail accounts which need EWS access may be enabled to access them, in particular an Impersonating account set up for RG Email Sidebar
  • Refer to this Microsoft article for details on enabling EWS access
  • Note that certain RG Email Sidebar functions may be not supported for this configuration (e.g. the Add-In will not be available, refer to this article for more information), contact our CSM team for details


Best practices configuration flow
  • Choose the RG Email Sidebar deployment model that suits your Org’s needs
  • Decide whether RG Email Sidebar IP address filtering shall be configured in your Org
  • Decide whether RG Email Sidebar EWS traffic filtering shall be configured in your Org
  • Decide which user authentication model shall be used in your organization: whether the end users will sign in to MS Exchange or Office 365 themselves, whether Exchange Impersonation and Service accounts will be used, and whether the RGES Outlook Add-In will be used; depending on that EWS access may be allowed only for a Service account authenticating a list of end users


EWS connection allows to establish MS Exchange or O365 (With Exchange Online) servers access to all data types at once: Emails, Calendar, Tasks, Contacts. The permissions set is called EWS.AccessAsUser.All; in contrast to MS Graph O365 access EWS does not have a technical possibility to limit access to specific data types.

>>> Click to see a screenshot <<<



Also see this FAQ entry for more information and this article to learn how to resolve the “Need Admin Approval” error



Customized data type specific access to mailboxes on O365 servers is available over MS Graph connection. See this article for details


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