POP3 or IMAP email?

This guide explains the differences between IMAP and POP3 connection protocols from email software (Outlook, Microsoft 365, Thunderbird, Apple Mail, eM Client, etc.). You will find other compatible protocols in this guide (click here) .

IMAP/IMAP4

Advantages : the emails remain on the server and are therefore accessible from any computer connected to the Internet, via kMail for example. Useful if your connection is permanent, if you want to access all your messages from several places simultaneously (at home, on the road, while traveling, etc.) and if several users share a service mailbox, from different workstations. You will always have the same view of the messages on the server, everyone will see the same messages: if a message is deleted by a user, the other users will no longer see this message. If moved to a folder on the server, all users will see this message in that folder.
Disadvantages: you must in principle be connected to the Internet to consult the messages (but certain messaging software, or messaging client, of certain mobile devices will allow you to display the inbox even without a 4G/5G or Wifi connection).

POP/POP3

Advantages : emails are removed from the server and sent to the computer. They can therefore be consulted even without an Internet connection. Convenient if your connection is expensive or not permanent
Disadvantages : emails no longer appear on kMail . You cannot be more than one to consult the same box because the messages being deleted at each consultation, you will have the impression of missing or seeing certain messages disappear. Also, if you "keep a copy of messages on the server" (mail client option), the more the number of mails kept as duplicates, the greater the risk of encountering problems. Learn more

The IMAP protocol not being compatible with the POP3 protocol, do not try to connect to  kMail when an email client configured in POP3 is open.