Einstein Activity Capture — Streamed Emails Not Appearing on Account Record Activity Timeline

When Einstein Activity Capture (EAC) captures emails and associates them to an Account record, only emails from the first 50 directly related Contacts appear in the Account's activity timeline. The first 50 Contacts are determined by Contact Record ID in ascending order.
Einstein Activity Capture is a Salesforce feature that syncs emails and calendar events between Salesforce and external email providers such as Gmail or Microsoft Exchange. Unlike standard Salesforce email records, emails captured by EAC are not stored as EmailMessage records in the Salesforce database. Instead, they are stored in an Amazon Web Services (AWS) database. The Salesforce user interface displays these streamed emails, but custom logic, Salesforce APIs, and reports do not apply to them.
This 50-Contact limit is a known limitation of Einstein Activity Capture and exists to accommodate relationship handling and association logic maintained on the AWS side. Salesforce does not have direct control over this limit.
To identify which Contacts are in the first 50 for a given Account, run the following query in Salesforce Developer Console or Workbench:
Query Contacts linked to an Account ordered by Record ID (ascending):
SELECT Id, AccountId, Email, LastModifiedDate, Name FROM Contact WHERE AccountId = 'Account record ID' ORDER BY ID ASC
Replace 'Account record ID' with the 18-character Salesforce Account ID. The first 50 results returned represent the Contacts whose emails are streamed to the Account activity timeline.

Refer to Einstein Activity Capture Security Guide for more information about Einstein Activity Capture security settings.