IMAP Port Number: IMAP, POP3 and SMTP Settings

The imap port number is usually 993 when your email app uses SSL/TLS, while the older IMAP port is 143. For a complete mailbox setup, use POP3 port 995 with SSL/TLS, or SMTP port 465 with SSL/TLS or 587 with STARTTLS.

Port numbers at a glance

Use this table when an email app asks for incoming and outgoing server values. The secure choices are the normal starting point for a new mailbox; use 143 or 110 only when your email provider specifically tells you to use STARTTLS or another supported mode.

Job	Protocol	Port	Security setting	What it does
Receive and sync mail	IMAP	993	SSL/TLS	Keeps mail and folders synchronised across devices
Receive and sync mail	IMAP	143	STARTTLS, if supported	Starts on the standard IMAP port and upgrades the connection
Download mail	POP3	995	SSL/TLS	Downloads messages to an email app
Download mail	POP3	110	STARTTLS, if supported	Legacy POP3 connection that can upgrade to TLS
Send mail from an app	SMTP submission	465	SSL/TLS	Encrypts the connection immediately
Send mail from an app	SMTP submission	587	STARTTLS/TLS	Connects first, then negotiates encryption
Mail transfer between servers	SMTP	25	Server policy and TLS	Used for SMTP transfer, not normally for a person’s mailbox app

The IANA service and port registry records the assigned services. The IETF’s RFC 8314 documents implicit TLS on 993, 995 and 465, and explains the role of STARTTLS on 587.

Port numbers are not passwords or DNS records. They are TCP connection doors that tell the app which mail service to contact. A correct server name with the wrong port can fail just as surely as a wrong password.

IMAP vs POP3: which should you use?

IMAP and POP3 are both incoming-mail protocols, but they behave differently after a message reaches your inbox.

IMAP keeps devices in sync

IMAP normally leaves messages on the mail server and synchronises the mailbox with each connected app. If a shop checks orders@yourdomain.tld on a phone and a computer, both devices can show the same inbox, read status, folders and sent messages.

Choose IMAP when:

• more than one person or device needs to see the same mailbox;
• you want to read a message on your phone and find it already marked read on your computer;
• you use folders, drafts and Sent items from different devices;
• you want the mailbox to remain available through webmail as well as an app.

The preferred secure IMAP setup is port 993 with SSL/TLS. Port 143 can support STARTTLS when the mail service offers it, but do not select plain or unencrypted access just because an app lists it.

POP3 downloads mail to an app

POP3 is designed mainly to retrieve messages to one email client. Depending on the client setting, it may download messages and leave a copy on the server, or remove them after download. It does not provide the same multi-device folder and read-status synchronisation as IMAP.

POP3 can make sense when one computer is the main place where you handle a mailbox and you deliberately want local downloads. If a shop uses one address on a phone and PC, IMAP is usually easier to manage because the mailbox remains one shared view.

The secure POP3 setup is port 995 with SSL/TLS. If you choose POP3, look for a setting such as Leave a copy on the server before downloading mail from a second device. That setting helps prevent one app from taking messages away from the other app, but it does not turn POP3 into full IMAP synchronisation.

The newer IMAP4rev2 specification describes 143 as the cleartext/STARTTLS port and 993 as the implicit-TLS port. The important practical rule is simple: use IMAP for shared, synchronised access and POP3 for a deliberate single-client download workflow.

SMTP ports: 465 vs 587 vs 25

SMTP is the outgoing side of email. Your app uses it when you send a message, even if your incoming mail is configured with IMAP.

Port 465: SSL/TLS from the beginning

Port 465 uses implicit TLS, often displayed in an app as SSL/TLS or SSL. Encryption starts as soon as the connection opens. Use it when your provider’s instructions specify 465 and SSL/TLS.

Port 587: STARTTLS submission

Port 587 is the standard choice for authenticated message submission in many email apps. The app connects to the SMTP service and then requests STARTTLS to encrypt the session. In an app, the security option may appear as STARTTLS, TLS, or TLS (if available); choose the option that requires a secure connection when available.

RFC 8314 describes both 465 implicit TLS and 587 STARTTLS for SMTP submission. If one is not accepted by your provider, do not swap the port randomly: check the provider’s mailbox instructions and match the encryption mode to the port.

Port 25: do not use it as your first choice

Port 25 is the registered SMTP port and is commonly used for mail transfer between servers. It is not the normal first choice for a person configuring a phone, Outlook or Gmail app to send through a mailbox. Use authenticated submission on 465 or 587 unless your provider explicitly documents another arrangement.

SMTP authentication is separate from the port number. Turn on authentication required and use the full mailbox address, such as orders@yourdomain.tld, with that mailbox’s password. If your app can choose “same settings as incoming server”, that is normally the useful option for a domain mailbox.

SSL/TLS settings that go with each port

The port and security setting must agree. Think of the pairing as one value, not two independent choices.

Port	Correct pairing	Avoid pairing it with
993	IMAP + SSL/TLS	STARTTLS-only mode, unless the provider says so
143	IMAP + STARTTLS, if offered	Plain login with a mailbox password
995	POP3 + SSL/TLS	STARTTLS-only mode, unless the provider says so
110	POP3 + STARTTLS, if offered	Plain login with a mailbox password
465	SMTP + SSL/TLS	STARTTLS mode
587	SMTP + STARTTLS/TLS	Immediate SSL/TLS mode, unless the app labels it correctly

Implicit TLS means encryption begins immediately after the connection opens. STARTTLS means the app starts the protocol conversation and then asks the server to upgrade that same connection to TLS. Both can protect a connection when configured and negotiated correctly, but a mismatch can produce an SSL error or a failed connection.

Use a server name covered by the mail server’s certificate. Do not ignore a certificate warning or replace the server name with an IP address just to make the error disappear. The certificate name and the server name must agree for a secure connection.

Example settings for a hosting mailbox

Before entering values, create the mailbox in your hosting panel and keep its exact password ready. If you need the full setup process, read how to create an official email ID with your domain.

In the example below, mail.yourdomain.tld is a placeholder. Replace it with the incoming and outgoing mail hostname shown in your hosting welcome details or control panel. Do not assume that every hosting account uses the same hostname.

Email app field	Value
Email address	orders@yourdomain.tld
Username	Full email address: orders@yourdomain.tld
Password	The password for this mailbox
Incoming protocol	IMAP
Incoming server	mail.yourdomain.tld
IMAP port	993
IMAP security	SSL/TLS
Outgoing server	mail.yourdomain.tld
SMTP port	465 with SSL/TLS, or 587 with STARTTLS/TLS
SMTP authentication	On; use the same full email address and mailbox password

For a POP3 setup, change only the incoming protocol, incoming port and security: choose POP3, port 995, and SSL/TLS. Keep SMTP enabled for outgoing mail. Never use your hosting-panel login unless the provider specifically says that it is also the mailbox password.

HostKarle DirectAdmin plans include domain mailboxes with IMAP and POP3 access. The DirectAdmin hosting page explains where email accounts are managed; use the exact mail hostname supplied for your account when configuring an app.

Common errors when a port is wrong

“Connection timed out” or “Cannot connect to server”

Check the server name first, then check the port. For incoming mail, try IMAP 993 with SSL/TLS or POP3 995 with SSL/TLS. For sending, try SMTP 465 with SSL/TLS or 587 with STARTTLS/TLS as documented by the provider.

If the app is set to use a proxy, VPN or office firewall, test the same mailbox on a different network. A timeout is a connection problem; changing the password will not usually fix it.

“SSL error”, “wrong version” or “certificate error”

The security mode and port may not match. For example, SMTP 465 should use immediate SSL/TLS, while SMTP 587 should use STARTTLS/TLS. Also check that the server name is the hostname supplied by the provider and that your device date and time are correct.

Do not accept a certificate warning permanently. Re-enter the correct hostname and use the secure port pair supplied for that mailbox.

Receiving works but sending fails

Incoming and outgoing mail use separate settings. Recheck the SMTP server, SMTP port, encryption mode and authentication required option. Choose “use same username and password as incoming” if your app offers it, then enter the full email address as the username.

“Authentication failed” or “invalid credentials”

This message usually points to the username or password, not the port. Use the complete address, including the domain, and reset the mailbox password in the hosting panel if necessary. A personal Gmail password, hosting-panel password or domain registrar password is not automatically the mailbox password.

Messages arrive on one device but not another

Check whether one device was configured with POP3. For a shared shop mailbox, configure both devices with IMAP 993 and SSL/TLS, then allow time for folders and messages to synchronise. Also check that both apps are using the same mailbox address rather than one using an alias or forwarding address.

If messages reach the inbox but later disappear or go to spam, the port is not the first thing to change. Use the guide on fixing emails that go to Gmail’s spam folder and check the mailbox, DNS and sending settings separately.

A quick setup checklist

Before saving an email account, confirm these six points:

1. You chose IMAP for multi-device synchronisation or POP3 for a deliberate download-only workflow.
2. IMAP uses 993 with SSL/TLS, or POP3 uses 995 with SSL/TLS.
3. SMTP uses 465 with SSL/TLS or 587 with STARTTLS/TLS.
4. The username is the full email address, not just the part before @.
5. SMTP authentication is enabled with the mailbox credentials.
6. The server name is the provider’s hostname and matches the secure certificate.

Send a test message to a second address, reply to it, and confirm the reply appears in the Sent folder on every IMAP device. Then send a message from the second address back to the domain mailbox. This checks outgoing SMTP, incoming IMAP, authentication and synchronisation in one short test.

FAQ

What is the IMAP port number?

The secure IMAP port number is 993 with SSL/TLS. Port 143 is the standard non-implicit-TLS port and may be used with STARTTLS when the provider supports it.

Is IMAP port 993 better than 143?

For a new mailbox, 993 with SSL/TLS is the simpler secure choice because encryption starts when the connection opens. Use 143 only when your provider or email app specifically requires STARTTLS on that port.

What is the POP3 port number?

Secure POP3 uses port 995 with SSL/TLS. Port 110 is the older POP3 port and should be used only with a documented secure STARTTLS configuration, not with an unprotected mailbox password.

Should SMTP use 465 or 587?

Use 465 with SSL/TLS when the app expects implicit TLS, or 587 with STARTTLS/TLS when it expects an authenticated submission connection. The correct choice is the one your email provider documents, and the security mode must match the port.

Can I use IMAP on my phone and computer at the same time?

Yes. IMAP is designed to keep a mailbox synchronised across multiple clients. Configure both devices with the same full email address, the same IMAP server and port 993 with SSL/TLS, then verify that Sent and custom folders are also synchronising.

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