Sync
A sync in Salesforce is a process that keeps records consistent between Salesforce and another system, so a change made in one place shows up in the other.
Definition
A sync in Salesforce is a process that keeps records consistent between Salesforce and another system, so a change made in one place shows up in the other. The "other system" might be a Microsoft or Google mailbox, a Data Cloud activation target, a marketing platform, or a custom backend reached through an API.
Sync is an umbrella term, not a single feature. Different jobs call for different mechanisms. Email and calendar run on Einstein Activity Capture, which replaced the retired Lightning Sync. Segment data flows out through Data Cloud activations. Record changes stream to outside systems through Change Data Capture. Each pattern has its own direction, timing, and limits.
The sync patterns and when each one fits
One-way versus bidirectional, and why the difference matters
Every sync moves data in one direction or two. A one-way sync has a clear source and a clear destination. The source is authoritative, the destination just receives, and there is never a question about which copy is correct. Data Cloud activations work this way. Segments leave Salesforce and land in an external platform, and nothing flows back along that path. A bidirectional sync lets both sides write, which is far harder to get right. The moment two systems can both edit the same record, you have to decide what happens when they disagree. Einstein Activity Capture syncs calendar events in both directions, and Salesforce documents that it gives preference to changes made in the connected Microsoft or Google calendar when a conflict occurs. The practical rule is to avoid bidirectional sync unless the business genuinely needs both sides to write. One-way is cheaper to build, cheaper to monitor, and almost never corrupts data on its own. Reach for two-way only when users truly edit the same record in both places and both edits have to stick.
Einstein Activity Capture for email and calendar
Einstein Activity Capture, often shortened to EAC, is the native way to connect a Microsoft 365 or Google Workspace account to Salesforce. Once a user links an account, EAC captures emails and calendar events and adds them to the activity timeline on related contact, lead, account, and opportunity records. Email can sync as full messages or as header-only metadata, depending on how the admin configures the capture settings. Calendar events sync in both directions. A meeting created in Outlook appears in Salesforce, and a meeting created in Salesforce appears in the connected calendar. EAC matches attendees to existing contacts and leads automatically, so the event lands on the right timeline without manual entry. Two details trip people up. First, the initial sync is not instant. After a user connects an account, Salesforce notes it can take up to 24 hours for past emails and events to appear. Second, EAC stores captured activity data using public cloud infrastructure rather than as standard Salesforce records, so some activity does not behave like a normal Task or Event record in reports.
Lightning Sync, the retired predecessor
Before EAC, the native email and calendar sync product was called Lightning Sync, and before that, Salesforce for Outlook. Lightning Sync handled contacts and events between Salesforce and Exchange or Google, and admins configured it through sync configurations that mapped which users and which records were in scope. Salesforce retired Lightning Sync and now points customers to Einstein Activity Capture as its replacement. The company publishes migration guidance for moving from Lightning Sync to EAC, including how to recreate the equivalent sync behavior. If you inherit an older org that still references Lightning Sync, treat it as legacy and plan the move rather than building anything new on top of it. The reason the switch matters is that the two products store data differently. Lightning Sync created standard records that lived in your org. EAC captures activity into its own store and surfaces it on the timeline. That difference affects reporting, data retention, and how you think about ownership of the synced data, so a migration is a real project, not a setting flip.
Data Cloud activations for segment data
Data Cloud, recently rebranded as Data 360, builds unified customer profiles by stitching together data from many sources. An activation is the process that publishes a Data Cloud segment to an external platform so the audience can be used there. This is a one-way sync from Data Cloud out to the destination. The list of destinations is broad. You can send a segment to Marketing Cloud Engagement, to advertising partners such as Google, LinkedIn, Meta, and Amazon Ads, to AppExchange partners like LiveRamp, and to cloud storage targets including Amazon S3, SFTP, Microsoft Azure Blob Storage, and Google Cloud Storage. Each activation carries the segment membership plus any related attributes you choose to include. Activations refresh on a schedule, so the synced audience is as current as the last publish. Salesforce also offers a rapid segment publish option to shorten the refresh interval when a slower cadence is not fast enough. When you delete an activation, Data Cloud stops sending data to the downstream systems tied to it, which is the clean way to switch a destination off.
Change Data Capture for streaming record changes
Change Data Capture, or CDC, keeps an external system current without periodic exports and imports. Instead of polling Salesforce on a timer, the external system subscribes to a stream and receives a change event whenever a record is created, updated, deleted, or undeleted. That makes it a near real-time, one-way feed of changes from Salesforce outward. Each change event includes the new and changed field values along with a header that describes what happened. The header carries details like the change type and the affected record. CDC is available for all custom objects and a supported subset of standard objects, and admins pick which objects emit events on the Change Data Capture setup page. Events flow on the standard channel by default. CDC is the right tool when an external data store has to mirror Salesforce closely and you cannot tolerate the lag of a nightly batch. It pairs well with middleware that consumes the stream and writes into the target system. Because it is one-way, CDC handles the Salesforce-to-outside half of a sync. If the outside system also needs to write back, that return path is a separate integration you build on top.
Conflict resolution, error handling, and monitoring
Three problems separate a sync that survives in production from one that quietly breaks. The first is conflict resolution. In any bidirectional sync you must decide which side wins when both change the same field. EAC resolves calendar conflicts by favoring the connected calendar, but a custom integration has no default, so you have to define the rule yourself, ideally per field. The second is error handling. Syncs fail for ordinary reasons: a record is locked, a required field is missing, an API limit is hit. Decide in advance whether a failed item retries automatically or moves to a dead-letter queue for a human to inspect. Silent drops are the worst outcome, because the two systems drift apart with no signal. The third is monitoring. You want a dashboard that shows sync lag and failure rate so you catch trouble before users report missing data. Salesforce gives EAC admins a way to test a user's sync status, and Data Cloud surfaces activation status. For custom syncs, build the equivalent visibility yourself. Reach for Salesforce-native options first, since they carry far less maintenance cost than a hand-built integration.
How to set up Einstein Activity Capture sync
The most common sync an admin turns on is Einstein Activity Capture, which connects users' Microsoft or Google email and calendar to Salesforce. Set it up once at the org level, then add the users or profiles who should sync.
- Open the Einstein Activity Capture setup
In Setup, use Quick Find to open Einstein Activity Capture, then start the guided setup to create a configuration. A configuration bundles your capture and sync choices and the people they apply to.
- Choose the email and calendar sync settings
Decide whether email syncs as full messages or header-only, and whether calendar events sync in both directions. These choices affect privacy and what appears on the activity timeline, so confirm them with stakeholders before saving.
- Assign users or profiles
Add the users, profiles, or permission set holders who should be included in this configuration. Only assigned users have their email and calendar captured.
- Have each user connect their account
Each assigned user connects their Microsoft or Google account from their personal settings under Email and Calendar Accounts. After connecting, allow up to 24 hours for past activity to appear.
Full message captures the email body and metadata; header-only captures just sender, recipients, and subject for tighter privacy.
Choose one-way or bidirectional event sync. Bidirectional lets edits flow both ways but introduces conflict handling.
Scope the configuration to specific users or profiles so only the intended people sync their accounts.
Decide whether captured emails and events are private to the user or shared with their team on related records.
- The first sync is not instant. Salesforce notes it can take up to 24 hours for past emails and events to populate after a user connects an account.
- EAC captures activity into its own store using public cloud infrastructure, so some synced items do not behave like standard Task or Event records in reports.
- For calendar events, EAC gives preference to changes made in the connected Microsoft or Google calendar when a conflict occurs.
- If your org still runs the retired Lightning Sync, migrate to EAC rather than running both, since the two store data differently.
Trust & references
Cross-checked against the following references.
Straight from the source - Salesforce's reference material on Sync.
- Activation for Data Cloud SegmentsSalesforce
- How Events Sync with Einstein Activity CaptureSalesforce
Hands-on resources to go deeper on Sync.
About the Author
Dipojjal Chakrabarti is a B2C Solution Architect with 29 Salesforce certifications and over 13 years in the Salesforce ecosystem. He runs salesforcedictionary.com to help admins, developers, architects, and cert/interview candidates sharpen their fundamentals. More about Dipojjal.
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