POP3 is designed to work as follows: the email client (Outlook, Thunderbird, etc.) connects to the email server and downloads emails to the computer/phone, then deletes the emails from the server.
There are additional settings to keep emails on the server after they are downloaded locally. This protocol is not suitable when a user wants to check the same email address on multiple different devices. POP3 will not show sent emails from one device when checking the same email address on another device. Also, if you delete an email from a local computer, the email will not be deleted from the server (if the option to keep emails on the server is enabled).
IMAP is an alternative protocol that meets today’s users’ needs. The local email client constantly syncs information between the email client and the server. When using IMAP, emails are downloaded to the local computer but also remain on the server. Synchronization is continuous regardless of how many devices the email account is set up on, including sent emails (emails in the Sent folder).
This protocol is much better suited for today’s users because the same email address is now checked on multiple devices. It allows the user to always see all emails, including sent ones. Whatever you do on the local email client actually happens on the server, so the user can check, send, or delete emails and see the same result on all devices using the IMAP protocol.
POP3 is still used by some people who check their mailbox on only one device and have limited server space. However, we do not recommend using POP3 because, for example, if the computer where the email address is set up fails, you will lose all emails (downloading emails via POP3 does not allow backing up email accounts).
Important! If you want to check the same email address on multiple devices, always use only IMAP on all devices.