What is the difference between POP3 and IMAP?
The e-mail protocols POP3 and IMAP handle retrieving of e-mails differently.
If the POP3 protocol is used for a mailbox, e-mails are deleted when retrieved from the mail server and are locally saved in the e-mail program. If e-mails are retrieved on a regular basis, the disk space needed on the mail server can be kept to a minimum.
When using IMAP for a mailbox, e-mails are not deleted from the mail server, but remain on the mail server. Similar to when calling up a website, an e-mail is only temporarily downloaded to view in the e-mail programme. When using IMAP, subfolders can be set up over the e-mail programme directly on the mail server to sort e-mails, for example. In addition, it is possible to save sent messages directly on the mail server. The advantage: You can retrieve your e-mails by Webmail mobil, for example – such as from your PC at home or at work. Note: When using the IMAP protocol, more disk space is generally needed for a mailbox in the mail server storage space than when using POP3.
How do I decide, if a mailbox is a POP3 mailbox or an IMAP mailbox?
Mailboxes can always be accessed either by POP3 or by IMAP. It is not necessary to define a particular protocol when setting up a mailbox in the account. You define at the time you set up the account in your e-mail programme, whether you want to access your mailbox by POP3 or IMAP.