If the group’s owner has allowed it, you can download the message archive for the group:

1. At the top of any message view page, look for and click or tap the Export Group Data button.
   Note: 
   • On a mobile device, you might need to use landscape orientation to see the button.
   • If you do not see this button at all in a desktop browser, mobile browser, or the mobile app, the group’s owner has not allowed members to download the message archive.
2. On the resulting page, in the Data to Export panel, select the Messages checkbox (it will be the only option).
3. Click or tap the Export Group Data button below the Data to Export panel. Groups.io displays a green banner at the top of the page stating that your request has been submitted and that you can expect an email with a link to download a zip file (a compressed archive file) within 10 minutes.
4. When you receive the email (the sender is Groups.io User Export Service, and the subject is “Export of [the group’s email address]”), click the Download Group Export link, and open or save the zip file.
   Note: The download link in the email is valid for 24 hours.

The zip file contains the message archive in mbox format, which you can open using an email client such as Mozilla Thunderbird or Apple Mail.