The service provides clients with access to Exchange functionality, which reduces the number of steps required for user configuration and deployment. In the case of Exchange Web Services (EWS) clients, the Autodiscover service is typically used to determine the EWS endpoint URL. However, Autodiscover can also provide information for configuring clients that use other logs. The service supports client applications inside and outside firewalls as well as client applications in resource structures and environments with multiple complete structures.

Difference between ELOxc and Autodiscover

To explain the differences between ELOxc and the Autodiscover service, the ELOxc configuration is described in more detail below.

ELOxc requires endpoints in the form of mailboxes for processing. These endpoints are associated with an SMTP address and credentials (pair consisting of a public ID and a secret key, usually logon and password). This is all ELOxc requires to use Autodiscover.

Moreover, ELOxc should not need any more, since it cannot do the job of Autodiscover. Accordingly, the system administrator must ensure that a request in the local domain that ELOxc is installed to is successful. The administrator requires the SMTP address used followed by the valid credentials after the endpoint is determined.

If the Autodiscover endpoint is in the local domain, there are usually no resolution problems. However, if the endpoint is in a different domain, the local domain needs to make the domain shown in the SMTP address available for Autodiscover. This usually requires a DNS pointer that automatically points the domain to the responsible Autodiscover service.

While the endpoint is being resolved, Autodiscover sends a request to ELOxc to validate the change in the processing logic. For this reason, you need to specify the ELOxc parameter "AutodiscoverRedirection" or "AccessUrl", since the ELOxc user must agree to the redirect as it could theoretically redirect to unwanted endpoints. Once the endpoint has been successfully validated, a request is sent to the responsible Exchange server to determine the EWS interface language. Authentication now takes place. It was not possible before since the target Exchange server address could not be resolved.

As we cannot always assume that the ELOxc domain is the same as the Exchange domain, we need to consider the role of Autodiscover in large and heterogeneous system environments.

Autodiscover is the responsibility of the system administrator. ELOxc cannot therefore be responsible for ensuring that Autodiscover resolution works. It makes sense to divide up these responsibilities because it enables central administration of background processes such as mailbox resolution or mailbox access. The bigger the system environment, the more important this aspect becomes.

We could express the expectations of ELOxc in relation to the system environment, albeit simply, as follows:

"Enable me to find and access the configured mailboxes, regardless of which domain I am currently in."

This is unequivocally the system administrator's task. ELOxc is dependent on a functioning system environment.

Difference between the domain and Autodiscover

For historical reasons, the ELOxc configuration contains a parameter for the domain that has been carried over from ELOxc MAPI. This parameter is only required for LDAP catalogs in order to determine an endpoint for the LDAP requests. Newer catalog endpoints such as PowerShell, EWS, or Azure Active Directory starting from ELOxc 12 do not require a domain specification.

It is clear from the "StaticLogins" in ELOxc that the catalogs require little configuration. These can be used to configure individual mailbox access without impersonation. However, this is likely to involve too much work above a certain limit. Catalogs enable you to reduce the amount of configuration needed. The domain is not especially important for Autodiscover since the target domain is primarily resolved from the SMTP address. However, the domain can be important for authentication of on-premise installations using LDAP catalogs to ensure that the credentials transferred for mailbox access are linked to a valid security concept. The ELOxc parameter "Domain" does not affect how Autodiscover locates the endpoints.