Sales Loves MarketingIMAP (Internet Message Access Protocol) is the protocol that lets an email app read and manage messages stored on a mail server. Your mailbox stays on the server, and every app you use, on your phone, laptop or in a browser, shows the same messages, folders and read status.
How does IMAP work?
Your email app connects to the mail server and asks for what it needs: the list of folders, the headers of new messages, or the full text of the one you open. It can fetch just part of a message, such as the text without the attachments, and ask the server to run searches instead of downloading the whole mailbox.
When you read, flag, move or delete a message, the app tells the server. The server stores that state, so your other devices see the change. Many apps also keep a local copy for offline reading, but the server copy is the master.
IMAP only covers reading and managing mail. Sending goes through a separate submission protocol (SMTP). The current version is IMAP4rev2, published by the IETF as RFC 9051 in August 2021. It replaced IMAP4rev1 (RFC 3501).
What is the difference between IMAP and POP3?
| IMAP | POP3 | |
|---|---|---|
| Where mail lives | On the server | Downloaded to one device |
| Multiple devices | Stay in sync | Each device sees its own copy |
| Folders and flags | Stored on the server | Kept locally |
| Partial download | Yes, e.g. text without attachments | Whole messages |
| Server storage needed | More | Less |
POP3 can still make sense for a single computer with a local archive. For most people who check email on several devices, IMAP is the better fit.
Which IMAP settings do you need?
An email app usually asks for:
- Incoming server name, such as
imap.yourprovider.com. Your provider's help pages list it. - Port and security. Use port 993 with TLS. RFC 8314 recommends implicit TLS for email access. Port 143 is for connections that start unencrypted.
- Sign-in. Many providers no longer accept a plain password from third-party apps. Gmail, for example, requires Sign in with Google and says IMAP is always on, so there is no setting to enable.
Why does IMAP matter for sales and marketing teams?
Sales teams often connect their mailbox to a CRM or sales tool so emails are logged against contacts. If a tool asks for IMAP settings, it uses IMAP to read and record the messages in your mailbox, so it can see everything that mailbox account can see. Check what access you are granting before you connect it.
IMAP also explains why an email read on your phone shows as read in your email client on your desktop: both are looking at the same server mailbox.
Related terms
Frequently asked questions
What is the difference between IMAP and POP3?
IMAP keeps your mailbox on the server and syncs it to every app, so reading or filing a message on your phone shows up on your laptop too. POP3 downloads messages to one device and usually leaves no shared state on the server. IMAP suits anyone who reads email on more than one device.
Which ports does IMAP use?
Port 993 for IMAP over TLS, which is the recommended option, and port 143 for connections that start unencrypted and may be upgraded with STARTTLS.
Do I need to turn on IMAP in Gmail?
No. Google's help says IMAP access is always turned on in Gmail, and the old enable and disable options were removed starting January 2025. Third-party apps must use Sign in with Google rather than your Gmail password.