IMAP and POP3 are the two standard ways a mail app reads your email. IMAP keeps mail on the server and keeps every device in sync; POP3 downloads messages to one device, traditionally deleting them from the server.
IMAP: the server is the source of truth
With IMAP, your mail stays on the server and your apps show a synchronised view of it. Read a message on your phone and it shows as read on your laptop; file it in a folder and the folder is the same everywhere. The current version is IMAP4rev2, RFC 9051.
POP3: download and (usually) delete
POP3 is older and simpler: the app downloads new messages, and by default the server removes them. It has no folders and no shared read state, so two devices using POP3 each see a different, partial inbox. The standard is RFC 1939.
Which should you use?
IMAP, almost always. POP3 still has uses — a single-device setup with very limited server storage, or deliberately taking mail offline — but for anyone with a phone and a computer, IMAP is the one that behaves the way people expect.
Sending is a separate protocol, SMTP, whichever of the two you read with.
IMAP and POP3 at Mailotte
Mailotte supports both, and SMTP for sending, on every plan including Free. Use port 993 for IMAP and 995 for POP3, both over SSL/TLS; there is no plaintext port. The mail clients page has every setting and step-by-step setup for Thunderbird, Apple Mail, phones and Outlook.
Questions
Should I use IMAP or POP3?
IMAP, unless you have a specific reason to keep mail on a single device. IMAP keeps every device in sync; POP3 does not.
What ports do IMAP and POP3 use?
The encrypted defaults are 993 for IMAP and 995 for POP3. The unencrypted ports, 143 and 110, should not be used — and at Mailotte they are not open.
Does POP3 delete my email from the server?
Traditionally yes, though most apps offer a setting to leave a copy on the server. That setting is a workaround for what IMAP does by default.
Related terms
- MX record — Mail Exchanger record
- MTA-STS — SMTP MTA Strict Transport Security
- Email alias — Email alias vs forwarder
- All terms