> ## Documentation Index > Fetch the complete documentation index at: https://docs.unifygtm.com/llms.txt > Use this file to discover all available pages before exploring further. # How bidirectional syncs work > An in-depth explanation of how syncs work between Salesforce and Unify. ## Overview Unify can create and update Salesforce records in response to Play runs and Sequence enrollments. This page summarizes the rules used to determine when and how to create or update records in Salesforce. ## Sync timing Salesforce read syncs are scheduled approximately every 15 minutes. When a large number of records change quickly in Salesforce, the next scheduled sync may take longer to complete, which can temporarily delay the appearance of new or updated records in Unify. When a Salesforce field mapping changes, Unify starts a background job to reprocess all records for the affected object. This does not interfere with the regular sync schedule, but it does mean that field mapping updates can take some time to be fully reflected in Unify. ## Overwriting data Unify takes a very conservative approach to overwriting existing Salesforce data to make data loss impossible. This approach is based around only a few simple rules: * **Creating new records:** When Unify is creating a new Salesforce record, it will fill in all fields that are enabled for writing in the field mapping or default values. * **Updating existing records:** Unify will inspect whether the field is empty or not. If the field is empty, it will be updated with the new value. If the field already has a value, it will only be updated if it is a Unify-specific field. These fields are prefixed with "Unify" and can be found [here](/reference/integrations/salesforce/field-mappings#available-fields). These rules apply regardless of how the record was originally created (e.g., by Unify or externally). If you're looking for more fine-grained control, you can also limit the permissions granted to the Unify integration user in Salesforce. ## Duplicate prevention Duplicates are strictly prevented within Unify. When creating new Salesforce records, Unify will only ever create one record. If there is already an existing Salesforce record of the same type, Unify will always update it rather than creating a new one. However, duplicates are a common problem in Salesforce and may already exist in your Salesforce instance. In addition, users or other integrations may accidentally create new duplicates over time. To accommodate this reality, Unify follows specific rules to ensure predictable behavior when updating duplicated Salesforce records. While Unify cannot de-duplicate your Salesforce, it will *never* make the problem worse, and in some situations may be able to help clarify the “source of truth” record. ## Supported objects Salesforce accounts are written by Unify whenever a contact is created or updated. They are also written if a Salesforce sync action runs within a Play that is running on companies. If there is an existing account that matches the Unify company being written, it will be updated. Matches are determined based on the domain of the company website. Domains are normalized, so URLs that redirect to different domains will not result in duplicates. If there are no matches, a new account will be created. If there are multiple accounts that match the Unify company, only one will be updated. Specifically, the account that was most recently modified within Salesforce will be updated. Salesforce contacts are written by Unify if **Create new records as Contacts & Accounts** is selected. In addition, contacts are sometimes created in place of leads if the person being written to Salesforce *already exists* as a contact. Unify cannot create a lead in this situation due to Salesforce’s [contact duplicate rules](https://help.salesforce.com/s/articleView?language=en_US\&id=sf.duplicate_rules_standard_contact_rule.htm\&type=5). In both situations, if there is an existing contact that matches the Unify person being written, it will be updated. Matches are determined based on email address. If there are no matches, a new contact will be created. If there are multiple contacts that match the Unify person, only one will be updated. Specifically, the contact that was most recently modified within Salesforce is the one that will be updated. Salesforce leads are written by Unify when **Create new records as Leads** is selected. If there is an existing lead that matches the Unify person being written, it will be updated. Matches are determined based on email address. If there are no matches, a new lead will be created. If there are multiple leads that match the Unify person, only one will be updated. Specifically, the lead that was most recently modified within Salesforce is the one that will be updated. Unify writes to the email message object in Salesforce, which is the recommended approach for syncing email data to Salesforce. To write records of this object type, the *Enhanced Email* feature must be enabled in Salesforce. This is typically enabled by default. Unify does not update existing email messages in Salesforce. Only emails sent through Unify or received in response to those emails will be written to Salesforce. Unify uses the standard **Universal Message ID** to deduplicate email messages if they are simultaneously being written by another integration. Email messages are written to Salesforce for emails sent as a part of Unify Sequences and for replies to those emails. The corresponding person must already exist in Salesforce as a contact or lead, or a Play action must sync the person to Salesforce before the email activity is written. Email messages can include mapped email activity fields such as subject, content, sent time, bounce status, click count, open timestamps, spam status, opt-out status, the enrolling Play, and Sequence name. These values are written only when the relevant event exists and the mapped Salesforce field is writable by the integration user. Unify writes eligible Unify tasks to the Salesforce Task object. This includes ready or completed non-email tasks, such as phone-call and action-item tasks, and completed email or reply tasks. Unify does not write email tasks to Salesforce before they are complete because email sending is controlled in Unify. Salesforce tasks are related to the corresponding Salesforce contact or lead. If the person does not already exist in Salesforce, Unify must sync the person to Salesforce before the task can be written. When there is an associated company and the person is a contact, Unify can also relate the task to the Salesforce account. When the person is a lead, Salesforce does not support the same account relationship on the task. Task sync uses Unify's standard Salesforce Task mapping rather than the company, person, or email message field mapping tables. Unify writes values such as subject, description, status, priority, task subtype, due date, owner, contact/lead relationship, and account relationship when available. When a task is deleted in Unify, Unify deletes the matching Salesforce task. Salesforce-to-Unify task sync is limited to completion updates. When a non-email Salesforce task that was written by Unify is marked **Completed** in Salesforce, Unify marks the corresponding task complete in Unify. Completed Salesforce phone-call tasks created by supported dialer integrations can also complete the matching open Unify phone-call task when Unify can identify a single matching task for the same person. Email tasks are excluded from this completion sync. Salesforce opportunities are read into Unify as opportunity records. They can be associated with companies and people when the Salesforce opportunity has the corresponding account or contact relationship. Opportunity data is primarily CRM-owned. Unify uses it for record context, filters, and exclusions, such as excluding companies with open opportunities from outbound Plays. Unify does not create or update Salesforce opportunities itself.