---
title: What Port Does IMAP Use? Technical Port Guide | SendHQ
description: Technical guide on IMAP port assignments for non-encrypted and encrypted connections including IMAPS and STARTTLS configurations.
canonical: https://sendhq.cc/terms/what-port-does-imap-use
last-updated: 2026-08-26
---
# What Port Does IMAP Use? Technical Port Guide

IMAP uses port 143 for non-encrypted connections and port 993 for encrypted connections via SSL/TLS. Port 143 is the standard port for the Internet Message Access Protocol, while port 993 is used for IMAPS, which provides a secure tunnel for email retrieval.

## Standard IMAP Port 143

Port 143 is the default assignment for IMAP. It supports cleartext communication and the STARTTLS extension. When using STARTTLS, the client connects to port 143 in plain text and then issues a command to upgrade the connection to a secure TLS encrypted session before transmitting sensitive credentials.

## Secure IMAP Port 993

Port 993 is used for IMAPS, which is IMAP over SSL/TLS. Unlike STARTTLS on port 143, port 993 establishes a secure connection immediately upon initiation. This implicit TLS approach is widely preferred for modern email clients to ensure that no data is transmitted in the clear.

## IMAP vs POP3 Ports

While IMAP allows multiple clients to sync with a server, POP3 is designed for downloading mail to a single device. POP3 uses port 110 for non-encrypted traffic and port 995 for secure SSL/TLS connections. Developers should choose IMAP ports when synchronization across devices is required.

## Configuration and Troubleshooting

When configuring email clients or backend services, ensure that the firewall allows outbound traffic on the selected port. If port 993 fails, verify that the server supports implicit TLS. For those managing complex mail flows, SendHQ provides free tools at https://sendhq.cc/tools to assist with general email configuration and verification.

## IANA Registration

The Internet Assigned Numbers Authority (IANA) maintains the official registry for service name and transport protocol port numbers. Both 143 and 993 are formally registered for the IMAP service to ensure global interoperability between different mail server implementations and client software.

## Questions teams ask

**What is the difference between port 143 and 993?**

Port 143 is for standard IMAP and uses STARTTLS for optional encryption. Port 993 is for IMAPS and requires a secure SSL/TLS connection from the start.

**Does IMAP use port 25?**

No, port 25 is used by SMTP for sending and relaying email, not by IMAP for retrieving email.

**Which IMAP port is more secure?**

Port 993 is generally considered more secure because it uses implicit TLS, meaning the connection is encrypted before any protocol commands are sent.

**Can I use IMAP on port 465?**

No, port 465 is traditionally used for SMTPS (Secure SMTP) and is not compatible with IMAP protocols.

## Primary sources

- [RFC 3501: Internet Message Access Protocol version 4rev1](https://www.rfc-editor.org/rfc/rfc3501) — RFC Editor
- [Service Name and Transport Protocol Port Number Registry](https://www.iana.org/assignments/service-names-port-numbers/service-names-port-numbers.xhtml) — IANA
- [RFC 8314: Cleartext Considerations for Post-SMTP Email Protocols](https://www.rfc-editor.org/rfc/rfc8314) — RFC Editor

## Continue learning

[smtp port](https://sendhq.cc/guides/smtp-port.md) [mail protocol smtp](https://sendhq.cc/guides/mail-protocol-smtp.md) [email deliverability](https://sendhq.cc/guides/email-deliverability.md)