Column Definitions (left to right):

• Gmail, etc. Support Status
• Email Address Lifespan
• Email Messages Lifespan
• Number of Domains Available.

Additional Details:

• Some services (ironically) let you keep generated emails indefinitely, either until you delete them or by using a feature that embeds the email address in the URL. When you visit the inbox page, you can usually see this in the URL, and in some cases, you can manually insert the address/username into the URL. This means the URL can act as a permalink to that mailbox, allowing you to bookmark it for continuous access. Therefore, sites with these features are marked with 'Forever' in the address lifespan column.