Message form postmaster saying I am over quota.

That means that you have too much mail stored on the mail server, and when you exceed your quota, your e-mail account will probably start bouncing e-mail. You need to figure this out quickly to avoid missing important e-mail messages.

I'm assuming that you are using Mail for your e-mail. If not, you're going to need to specify how you are accessing your e-mail.

In Mail, choose Preferences from the Mail menu. In the window that opens, click Accounts. You should see a list of the e-mail accounts you have set up, and underneath will be something that identifies the account type. It will say something along the lines of IMAP, POP, Exchange, iCloud IMAP, etc. What does that say?

If it's IMAP, you say you have deleted everything, but have you emptied the trash in Mail? If not, choose Mailbox -> Erase Deleted Items -> In All Accounts.

Sometimes Mail will not update the items on the server properly. Go to the Mail preferences and in the Accounts section choose the email account that is giving you problems. In here, choose "Mailbox Behaviors" and uncheck the options to store messages on the server. These options should be available for drafts, sent, junk, and trashed items.

You can also set the drop-down menus to remove sent, deleted, and junk items after a shorter period of time so they do not always persist on the server.

When done, open the "Activity" panel from the Window menu, and you should see the server updating, and hopefully removing enough items to give you the space you need. This may take a while, so let it do its thing.

Alternatively, if your email provider offers Webmail then log into that and use that to remove items. This should then update Mail accordingly, and also immediately give you the space you need.

Hi Thomas, I hve two accounts one is iCloud imap and the other one is shaw pop. Now I am not sure what one is giving me the problem.

You will need to look at the sender of the message saying you're nearing your quota. It should come from either iCloud/Apple or Shaw, and that will tell you which account is having the problem.

Note that POP does not involve syncing your mailbox with the server. If you have set the account not to delete messages after they have been downloaded, they could be piling up there. In Mail's Accounts preferences, select the POP account and click the Advanced tab.

If the box labeled "Remove copy from server...." is not checked, you should check it, and should click the "Remove now" button to immediately remove old messages. (Unless, of course, you have purposefully left messages on the server that you need.)