[IMP]Misc:SysParm-edits-email-doc

closes #4494

X-original-commit: 9267ce2
Signed-off-by: Timothy Kukulka (tiku) <tiku@odoo.com>

Author: tiku-odoo

content/applications/general/email_communication/email_servers.rst

@@ -271,3 +271,32 @@ By default, inbound messages are fetched every 5 minutes for on-premise database
    This value can be changed in :ref:`developer mode <developer-mode>`. Go to
    :menuselection:`Settings --> Technical --> Automation --> Scheduled Actions` and look for
    :guilabel:`Mail: Fetchmail Service`.
+
+System parameters that prevent feedback loops
+---------------------------------------------
+
+There are two system parameters that help prevent email loops from occurring in Odoo. These
+parameters were introduced in Odoo 16 to prevent aliases from creating too many records and to
+prevent feedback loops on the catchall reply-to email address. They are present in database but not
+in the *System Parameters*. To override the following defaults they need to be added in.
+
+The two system parameters are as follows:
+
+- `mail.incoming.limit.period` (60 minutes by default)
+- `mail.incoming.limit.alias` (5 by default)
+
+Add these fields in Odoo by first enabling :ref:`developer mode <developer-mode>`, and then
+navigating to :menuselection:`Settings --> Technical Menu --> Parameters --> System Parameters`.
+Change the value of these parameters, as needed.
+
+When an email is received in the Odoo database on the catchall email address or on any alias, Odoo
+looks at the mail received for the given period of time defined in the system parameter
+`mail.incoming.limit.period`. If the received email was sent to an alias then Odoo will reference
+the `mail.incoming.limit.alias` system parameter and determine the value as the number of records
+this alias is allowed to create in the given period of time (value of `mail.incoming.limit.period`).
+
+In addition, when email is received to the catchall email address, Odoo will reference the emails
+received to the database during the set period of time (as stated by the value in the system
+parameter: `mail.incoming.limit.period`). Odoo will then determine whether any of the emails
+received match that of the email(s) being received during the specified time-frame, and will prevent
+a feedback loop from occurring if a duplicate email is detected.