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Here's a quick explanation of some of the terms that are used when talking about email hosting.
An email client is a computer program that lets you read and send email. Microsoft Outlook, Mozilla Thunderbird and Windows Live Mail are all email clients. Email clients talk to email servers.
An email servers is a computer attached to the Internet that stores your email when others send them to you, and sends emails out on your behalf when you send an email from your mail client. Your hosting provider normally own and runs the email server. Email clients and servers talk to each other using protocols.
POP, IMAP and SMTP are protocols, they're the language that your email client uses to talk to the email server. The P at the end of POP, IMAP and SMTP stands for protocol.
IMAP allows you to view your email from more than one place. E.g. from your desktop computer at work and from your laptop at home and from abroad and from your mobile device - multiple locations. To use IMAP effectively, you need to make sure that each program on each computer that you use to view your email is set up to use IMAP.
With IMAP all of your email is stored on email server which has a quota limit. If you run out of space you will not be able to receive new emails into your account.
POP is suitable if you have no need to check your email in multiple locations. POP is older than IMAP, and, because IMAP allows you to check your email from more than one location easily, we recommend that you use IMAP.
POP and IMAP are both used to talk to the email server to get your email, SMTP is the name of the protocol that is used to send email.
We have a couple of pages to help get your email set up correctly: