Microsoft Data Retention and Destruction

While Purview options might be unavailable, you can still achieve yearly email purging and 30-day Teams chat deletion in your Microsoft environment without an E3 or E5 license. Here's how:

Email Purging:

Retention Policies: Utilize Exchange Online retention policies. These allow you to define rules for automatically deleting emails based on specific criteria like age, sender, recipient, or keywords.
Create a new retention policy with the following settings:
Retention period: Set it to "1 year" for emails from the previous year.
Apply to: Choose the mailboxes or groups where you want this policy applied.
Retention action: Select "Delete".
You can create separate policies with different retention periods for specific needs, like excluding certain individuals or departments.
Retention Tags: Alternatively, consider retention tags. These are pre-defined policies that can be applied to folders or individual messages.
Create a custom retention tag with a "1 year" retention period and apply it to relevant folders or emails.
Teams Chat Deletion:

Retention Policies: Unfortunately, native Teams chat retention policies aren't available without E3 or E5 licenses. However, you can leverage PowerShell cmdlets to achieve similar functionality.
Use the Remove-AzureADGroupChatMessage cmdlet to delete messages older than 30 days.
This method requires scripting knowledge and careful execution to avoid unintended data loss.
Manual Deletion: Encourage users to manually delete chats or channels exceeding the desired retention period.
Important Considerations:

Testing: Before implementing any deletion strategy, thoroughly test it in a non-production environment to ensure it functions as expected and doesn't affect crucial data.
Legal and Compliance Requirements: Ensure your data retention policies comply with relevant legal and regulatory requirements, as well as your organization's internal policies.
Backup and Recovery: Maintain proper backups of your data in case of accidental deletion or unforeseen issues.
Additional Resources:

Exchange Online retention policies: https://learn.microsoft.com/en-us/exchange/security-and-compliance/messaging-records-management/create-a-retention-policy
Retention tags: https://learn.microsoft.com/en-us/exchange/security-and-compliance/messaging-records-management/retention-tags-and-policies
Remove-AzureADGroupChatMessage cmdlet: https://learn.microsoft.com/en-us/powershell/module/azuread/remove-azureadgroupmember?view=azureadps-2.0
Remember, consulting with an IT professional familiar with your specific environment is recommended for setting up these configurations and ensuring data security and compliance.