Email setup: POP3, IMAP, SMTP settings and when to use which

POP3 and IMAP both receive mail; SMTP sends it. People mix them up constantly. This article lays out what each actually does, shows the exact settings for Omega Digital mail servers, and ends with a rule of thumb for picking the right combination.

What each protocol does

IMAP (Internet Message Access Protocol)

Leaves mail on the server. Every device (laptop, phone, tablet) sees the same inbox in real time. Mark something read on your phone and it's already read on your laptop. This is what you want 95% of the time.

POP3 (Post Office Protocol v3)

Downloads mail to one device and (by default) deletes it from the server. Sensible in 1998; usually wrong today. Useful in exactly two cases: offline-first single-device workflows and archival pulls where you want to clear server storage.

SMTP (Simple Mail Transfer Protocol)

Sends outgoing mail. Works alongside either IMAP or POP3. Port 465 (implicit SSL) or 587 (STARTTLS). Never port 25 from a client; residential ISPs block it and providers reject it.

Exact Omega Digital settings

Setting	IMAP	POP3	SMTP
Server	mail.yourdomain.com	mail.yourdomain.com	mail.yourdomain.com
Port (SSL)	993	995	465
Port (STARTTLS)	143	110	587
Encryption	SSL/TLS	SSL/TLS	SSL/TLS or STARTTLS
Username	full email	full email	full email
Auth	Password	Password	Password, same as incoming

We disable the plaintext ports 143 (IMAP), 110 (POP3), and 25 (SMTP) for client connections by default. If your mail client won't connect, it is almost always because it picked an unencrypted port.

A decision rule

01. One device, offline-first (a single laptop, frequent plane trips): POP3 with 'leave messages on server for 30 days'.
02. Two or more devices (phone + laptop + tablet): IMAP, always.
03. Shared inbox (hello@, support@, multiple people): IMAP with shared folders or forward to a ticketing system.
04. Archival pull from an old host before decommissioning: POP3, configured to delete from server.

Apple Mail example (IMAP + SMTP)

text

Account type: IMAP
Description: Work
Full name: Jane Doe
Email address: [email protected]

Incoming Mail Server:
  Host: mail.yourdomain.com
  Username: [email protected]
  Password: ••••••••
  Port: 993
  Use SSL: Yes

Outgoing Mail Server (SMTP):
  Host: mail.yourdomain.com
  Username: [email protected]
  Password: ••••••••
  Port: 465
  Use SSL: Yes
  Authentication: Password

Thunderbird example (IMAP + SMTP)

text

Incoming:
  Server type: IMAP Mail Server
  Server name: mail.yourdomain.com
  Port: 993
  Username: [email protected]
  Connection security: SSL/TLS
  Authentication method: Normal password

Outgoing (Tools → Account Settings → Outgoing Server):
  Server name: mail.yourdomain.com
  Port: 465
  Connection security: SSL/TLS
  Authentication method: Normal password
  Username: [email protected]

Mobile: iOS and Android

Both operating systems offer 'Other' as an account type. Skip auto-detection. It almost always picks wrong settings. Enter the values from the IMAP and SMTP columns manually. On iOS, the 'SSL' toggle must be on for both incoming and outgoing servers.

Common gotchas

· Mixing IMAP on one device and POP3 on another. The POP3 device deletes from the server, so the IMAP device sees mail vanish. Pick one protocol per mailbox across all devices.
· Wrong username. Always the full email ([email protected]), never just jane.
· ISP blocks port 25. Use 465 or 587. Never 25 for client submission.
· SSL certificate warning. Your mail client must connect to the hostname the certificate covers. If AutoSSL issued for mail.yourdomain.com, you must use that hostname exactly.

Still stuck?

Email [email protected] and include the exact client error message plus the device you're using.