To organize email support you need a mailbox on the organization's mail server, or on a public mail server. The server must support IMAP (or, as a last resort, POP3) and SMTP. The connection to the server can be protected by encryption (TLS or SSL).
You can use several email addresses, collecting Requests in one or more projects. Connections to the mail server are created in the module "Email addresses", or in the Administration section, in the "Support" menu.
Usually, emails are converted into Requests if the recipient is the support mailbox address. Sometimes, however, you need to work with aliases. That is, messages appear to be sent to different addresses, but actually arrive in the same mailbox. For such scenarios, use the Aliases field.
By default, when a Request is created from an email, the Request author receives an email notification that the Request has been added and is being handled. If this notification is not needed, clear the corresponding checkbox in the email address settings in ALM. Notification texts can be configured in the Administration section of the application, in the "Settings - Texts" menu.
To debug the mail processing mechanism, use the "Log" tab. It shows information about the most recent attempt to connect to the mail server.
Also note that support mailbox settings are not related to the mail settings of the ALM application itself. Sending mail from the application is configured in the Administration section.