Hi,
I am changing my web host. what will happen to my email when my I change hosting provider.

For this, you would be change the nameservers for your domain . In this case the DNS propagation period will mean that some emails destined for your domain will arrive at your old host, and some emails will arrive at your new host (providing you’ve configured mailboxes etc. before changing the nameservers!).

So in terms of receiving emails, it’s important to keep both old/new hosting accounts open during the changeover so that new emails aren’t lost – and also ensure that you check your old hosting provider for emails about 24 hours after you’ve changed the nameservers.

Regarding emails that you’ve already received downloaded it to your computer