If you change internet providers, your account is deleted, you lose your email address and access to that providers mail. It's deleted from the server, never to be seen again. Many have lost important emails and contacts after changing providers when they did not realize this would happen.
Using an email client, your mail will still be there. All you have to do is change the server information from the old provider to the new one.
You can also easily back up mail and contacts in a client. Most web mail will not allow you to back it up.
Some web based mail does not let one set up mail filters and rules. This can be done with an email client.
If you have multiple email accounts you can set them all up in the client. No need to go to different websites in order to read/send mail. I open my client. By default my primary ISP account mail is shown. When I want to look at mail sent to my secondary ISP account I click that account name in the list and immediately get switched to it.
No ads in email clients.
Easy access. Click an icon on my desktop, client opens and I don't have to sign in because I have it set up so I don't have to enter my password each time.
Edited by Queen-Evie, 22 June 2014 - 10:28 PM.