Blog | Onna

How to Seamlessly Migrate Slack and Gmail Data Without Losing Critical Information for Legal Holds

Written by Brendan Locke | Nov 13, 2025 1:00:00 PM

Seamlessly migrating Slack and Gmail data while preserving crucial information for legal purposes is entirely possible with the right approach. By preparing both platforms carefully, transferring data securely, and verifying that everything remains within the scope of your legal holds, you can make sure no critical records are lost and compliance is maintained.

Have you ever wondered how to meet the demands of legal holds when major communication tools like Slack and Gmail are involved?

Let's take a closer look at how to handle Slack eDiscovery, download Gmail information properly, execute Slack exports, and manage the Gmail data transfer, all as part of a robust legal hold data process.

Can Slack Messages Be Used in Court?

Slack eDiscovery allows companies to collect and review conversations that may be relevant to a case. Legal teams can use specialized tools to search through messages, files, and attachments. These records can then be presented as evidence, provided they've been maintained in a complete and unaltered state.

Slack exports are key for gathering messages and files. Standard exports capture public channel data, while corporate plans offer more advanced export options that include private messages. Setting the right retention rules helps prevent message loss and supports accurate recordkeeping.

What Is a Legal Hold?

A legal hold stops normal data deletion and protects information that could be needed in a lawsuit or investigation. When a company is asked to preserve records, it must freeze that data until the matter is resolved.

There are three main parts to this process:

  • Legal hold notification and activation
  • Data preservation and tracking
  • Compliance monitoring and risk prevention

Legal Hold Notification and Activation

When a legal hold begins, the legal team sends notices to employees whose data may be relevant. These notices tell them to stop deleting files or emails. In some systems, automated holds are applied to Slack and Gmail accounts to prevent accidental removal of key information.

Data Preservation and Tracking

The next step in the legal hold data process is to secure and monitor the information. Slack messages, emails, and attachments are stored in a protected archive.

This step helps protect email records and conversation histories that might support a legal case. Tracking which data has been locked also keeps the migration organized and compliant.

Compliance Monitoring and Risk Prevention

Ongoing review is necessary to confirm that preserved data stays intact. During a Slack data migration or Gmail data transfer, teams must check that no information under hold is altered or lost.

Regular audits help catch problems early and maintain trust in the process. Keeping data integrity at every step supports both compliance and reliability in future legal reviews.

Preparing Slack and Gmail Data for Migration

The first step is to review what data is stored in both platforms. Outdated or irrelevant files can be removed if they're not under a legal hold.

Identifying who owns what information also helps control access. This step prevents confusion later and makes it easier to track what has been migrated.

Slack exports give legal and IT teams the ability to collect:

  • Messages
  • Attachments
  • Related data

For companies with paid plans, exports can include private channels and direct messages, which are often part of compliance reviews.

Download Gmail Information Safely

Before transferring Gmail data, teams should download Gmail information using approved tools or Google's Takeout service. It includes emails, attachments, and metadata that might be required for a legal hold.

Verifying that downloads are complete and readable prevents problems during migration. Whether the goal is archiving or live transfer, confirming that the data matches the original Gmail account helps preserve accuracy and reliability.

Executing a Secure Data Migration

Choosing the right technology matters. A dependable migration platform, like Onna, supports Slack data migration and Gmail data transfer without changing or losing files.

It's important that tools can handle large volumes of data and preserve the original structure of messages and attachments. Testing small samples first helps confirm that transfers are working correctly before moving all data.

Applying Encryption and Chain of Custody Controls

Data protection starts with encryption. All transfers should use secure methods that keep information private from start to finish.

Maintaining a chain of custody means tracking every step of the data's movement. This record shows who handled it, where it went, and when the transfer occurred. These details are often required for legal review or compliance checks.

Maintaining Accurate Audit Trails for Verification

An audit trail records every action taken during the migration. This includes logs showing:

  • Who accessed files
  • When transfers occurred
  • Whether any errors appeared

These records support accountability and help prove that the migration followed security standards.

Frequently Asked Questions

What Happens If Data Is Lost During a Legal Hold Migration?

Losing data during a legal hold process can create serious compliance risks. If this happens, the first step is to document what was lost and when it occurred. Legal teams often review system logs to identify whether the data can be recovered from backups or mirrored storage.

Some organizations maintain redundancy plans that include daily snapshots of Slack and Gmail data. These backups allow them to restore information quickly while preserving the legal chain of custody. Failing to account for lost data can affect the credibility of legal evidence, so having a response plan is a key part of any secure data migration strategy.

How Can Companies Protect Gmail Attachments and Metadata During Transfers?

Attachments and metadata hold as much legal value as the emails themselves. Companies can protect these by using secure migration tools that support encryption and full data mapping.

During a Gmail data transfer, all file paths, timestamps, and sender information should remain unchanged. Some organizations run checksum tests to verify that files match before and after migration.

Secure Data Migration

Protecting records under legal holds not only safeguards information but also strengthens trust in every data management decision.

At Onna, we centralize your organization's unstructured data from cloud applications into one secure, scalable platform. Our Data Management Platform uses advanced AI, OCR, and NLP to make data searchable, manageable, and compliant. With flexible APIs, adaptable exports, and strong security controls, we simplify data access, collaboration, and governance across your digital workspace.

Get in touch today to find out how we can help with your Slack and Gmail data.