We're all used to having all our emails available in the cloud all the time, easily searchable and on all of our devices. But there are multiple points of failure to think about—what happens if something in the cloud breaks, or your connection to the internet does? What if your account gets banned or closed for whatever reason, and all of your email goes with it?
Those are only a few potential problems. You might accidentally delete a bunch of emails you didn't mean to; someone else could access your account and wipe everything they find; or your email provider might suddenly decide to lock you out.
With all that in mind, access to your email doesn't seem like such a given. It might not matter for all those newsletters, special offers, and account notifications that clog up your inbox, but what about emails and documents you really need access to? It helps to have at least some of your emails backed up in another location so that you can always get at them, offline or otherwise.
Forwarding emails is one way of backing them up.
Apple via David NieldThe simplest way to get all of your emails sent to another account is to forward them, either manually one by one or automatically as they come in. From iCloud Mail, for example, you can click the cog icon (bottom left), then choose Preferences and General: Tick the box next to Forward my email to and enter another email address.
If you open up Gmail on the web, click the cog icon (top right), then See all settings. Under Forwarding and POP/IMAP, tick the box labeled Forward a copy of incoming mail to and enter your secondary email address. Gmail actually lets you create a filter for forwarded emails (messages from a specific contact, for example), so you don't get everything forwarded—click the create a filter link next to Forwarding to do this.
Finally, for the Outlook web client, click the cog icon (top right), then View all Outlook settings, Email, and Forwarding. Tick the Enable forwarding box, enter the secondary email address you want to use, and all of the messages that arrive in your Outlook inbox will be sent on to the other account too. If something happens to your primary account, you can still at least reference your messages.