The major difference between POP and IMAP is that, IMAP always syncs with mail server so that any changes you make in your mail client (Microsoft Outlook, Thunderbird) will instantly appear on your webmail inbox.
On the other hand, in POP, your mail client account and mail server are not synced. It means whatever changes you make to your email account in the mail client will not be transferred to the webmail inbox.
In simple terms, if you are using IMAP and mark a mail as read, it gets marked as read in your web based inbox too (because the changes are happening on the server). However, this won’t be the case if you are using POP, because the mails are downloaded to your PC and the changes won’t reflect on the server.
The other difference is POP downloads the mail to your local system and leaves no mail in the actual mail server. While, IMAP keeps the original in the server and only downloads a copy to your local computer. So the advantage on using IMAP is that, you can check the mails from where ever you want since the mail originally exists in the server. With POP, once the mail is downloaded to your local system, you cannot find that mail even in your Webmail.
However, you can strictly ask the POP to keep the mails in server by enabling an option “Keep a copy of mails in the server” and “Delete the mails after n days”. All the major mail clients has this configuration option.
You can check more from below URL:
There is no issue in using IMAP. We impose no restrictions on IMAP/POP. You can select one based on your requirement.
POP3 is generally the preferred choice as the default quota for each inbox is only 250mb, this way the emails are constantly being download to the local machine and the inbox has the ability to stay below the 250mb quota.