What is email digest? Example with Odoo Digest

An email digest is an email that is automatically generated by an electronic mailing list and which combines all exchanged emails during a time period (e.g. day, week, month, etc.) or when a volume limit is reached (e.g. every 10 or 100 messages) into one single message.

Email digests are currently available as an opt-in feature in electronic mailing list systems such as GNU Mailman or LISTSERV. It is called an abridged summary in Google Groups. Other systems than mailing lists implement such a feature. YouTube compiles all the communications to users within a time period into a single email.

How often are digest emails sent?

Digest emails are sent approximately one hour after the first notification event, so Users will receive no more than one digest email per hour. 

Is this feature available to all Users?

Yes, the email digest functionality is available to all Users; however, only notifications sent to email addresses associated with actual Users get consolidated into the digest format. Emails sent to distribution lists or recipients that are not associated with actual Users such as "partners@yourdomain.com" or "channelmarketing@yourcompanyname.com" can't be consolidated to the digest format. 

For example: We can send periodic status emails from Odoo ERP automatically using Odoo digest. It is possible to configure the frequency of emails and the contents of the email.

Via wiki