Email server settings

Optimum IMAP settings and SMTP server

Q: What are the Optimum IMAP settings?

Server mail.optimum.net, port 993, SSL, with your full optimum.net address as the user name and the password of that address. Optimum recommends IMAP if you read mail on more than one device.

Q: What is the Optimum SMTP server?

mail.optimum.net on port 465 with SSL. Turn on outgoing authentication (“My outgoing server requires authentication”) with the same settings as the incoming server.

Q: What are the Suddenlink email settings?

IMAP imap.suddenlink.net on 993, POP3 pop.suddenlink.net on 995 and SMTP smtp.suddenlink.net on 465, all with SSL, and your full suddenlink.net address as the user name.

The Optimum IMAP settings are mail.optimum.net, port 993 with SSL, and your full optimum.net address as the user name. Outgoing mail uses the same host, mail.optimum.net, on port 465 with SSL, and the outgoing server must require authentication. Suddenlink addresses use their own servers.

Last checked October 10, 2026, against Optimum’s own documentation.

Optimum and Suddenlink email servers

Server, port and securityServer	Port and security
IMAP · incomingmail.optimum.net993 · SSL/TLSoptimum.net addresses; recommended	993SSL/TLS
POP3 · incomingmail.optimum.net995 · SSL/TLSoptimum.net addresses	995SSL/TLS
SMTP · outgoingmail.optimum.net465 · SSL/TLSoptimum.net addresses; authentication required	465SSL/TLS
IMAP · incomingimap.suddenlink.net993 · SSL/TLSsuddenlink.net addresses	993SSL/TLS
POP3 · incomingpop.suddenlink.net995 · SSL/TLSsuddenlink.net addresses	995SSL/TLS
SMTP · outgoingsmtp.suddenlink.net465 · SSL/TLSsuddenlink.net addresses; authentication required	465SSL/TLS

Sign-in: Full address + email password

User name: your full email address, including the domain, for example jane.doe@optimum.net or jane.doe@suddenlink.net; the password is the one for that email address.

Optimum SMTP and IMAP settings explained

The values come from Optimum’s FAQ Can I access my Optimum or Suddenlink email using an email client?. It covers both Optimum and Suddenlink addresses, which use different servers but the same ports.

One host for Optimum. mail.optimum.net handles incoming and outgoing mail; only the port changes. Suddenlink splits it into imap.suddenlink.net, pop.suddenlink.net and smtp.suddenlink.net.
SSL ports only. Optimum lists 993, 995 and 465, each marked as a secure connection “recommended if your mail client supports” it. The FAQ lists no port 587 and no STARTTLS option.
IMAP over POP. Optimum recommends IMAP if you read mail on more than one device. POP downloads messages without leaving a copy on the server, so a deleted or read message on one device isn’t reflected on the others.
No new accounts. As of May 4, 2021, Optimum no longer lets new or existing Internet customers create new Optimum email accounts. Existing addresses keep working with the settings above.

Optimum’s FAQ asks for two things in every mail app:

User name = full email address, “including the @domain.net at the end”, so jane.doe@optimum.net, not just jane.doe. The password is the one for that email address.
Outgoing authentication on. If your app has a checkbox such as My outgoing server (SMTP) requires authentication, check it and choose Use same settings as my incoming mail server.

The FAQ doesn’t mention app passwords or OAuth sign-in for Optimum email; mail apps log in with the address and its password.

Optimum IMAP settings for iPhone, Outlook and Thunderbird

Optimum names Gmail, Outlook.com, Yahoo Mail and the Mail app on iPhone or Android as clients that work with these settings.

iPhone and iPad: Settings → Apps → Mail → Mail Accounts → Add Account → Add Other Account → Mail Account. Enter name, address and password, choose IMAP, and use mail.optimum.net as the incoming and the outgoing server (Suddenlink: imap.suddenlink.net and smtp.suddenlink.net), with the full address as the user name on both. If sending fails, set the outgoing server to port 465 with SSL under the account’s advanced settings.
Outlook: add the account manually as IMAP: incoming mail.optimum.net, 993, SSL/TLS; outgoing mail.optimum.net, 465, SSL/TLS. Under the outgoing server settings, turn on authentication with the same settings as the incoming server.
Thunderbird: use manual configuration with the same hosts and ports, connection security SSL/TLS, and the full address as the user name for IMAP and SMTP.
Android and the Gmail app: add an Other or IMAP account with the values from the table.

Common Optimum email problems

Error or symptom	Fix
Receiving works, sending fails	Outgoing authentication is off or the port is wrong. Use `mail.optimum.net` on port 465 with SSL and check My outgoing server requires authentication with the same login as for incoming mail.
Password rejected	The user name is incomplete. Enter the full address, including `@optimum.net` or `@suddenlink.net`, on both servers.
A Suddenlink address doesn’t connect	Suddenlink uses its own hosts: `imap.suddenlink.net`, `pop.suddenlink.net` and `smtp.suddenlink.net`, not `mail.optimum.net`.
Messages are missing on your phone or second computer	One device uses POP, which downloads mail without leaving a copy on the server. Switch every device to IMAP.
You want a new Optimum email address	Not possible: Optimum stopped creating new email accounts on May 4, 2021.

Optimum’s FAQ doesn’t quote error texts. If a message you send bounces, the reply code says why: see the SMTP error codes and the difference between a hard vs. soft bounce.

Is @optimum.net still a valid email domain?

Yes, for existing accounts. optimum.net is the email domain of Optimum Internet customers, and the servers above still accept mail apps. Because nobody has been able to create a new Optimum address since May 4, 2021, every optimum.net contact on your list is at least that old, and addresses from closed accounts come back as a hard bounce.

Before a mailing to an older list, run it through a bulk email verifier, or check one contact with is this a real email address. The live MX records box on this page shows where optimum.net mail is delivered today; other ISP addresses in the same situation are covered on the Cox.net SMTP settings and Comcast IMAP settings pages.

Both domains that mail apps set up with these servers

optimum.net, suddenlink.net.

Source: Optimum’s email client FAQ, which covers optimum.net and suddenlink.net addresses.

Sources

Checked on October 10, 2026. Server names, ports and sign-in rules come from these official pages:

Optimum FAQ: Can I access my Optimum or Suddenlink email using an email client?

Other internet providers

Optimum email settings: FAQ

What are the Optimum IMAP settings?

Server mail.optimum.net, port 993, SSL, with your full optimum.net address as the user name and the password of that address. Optimum recommends IMAP if you read mail on more than one device.

What is the Optimum SMTP server?

mail.optimum.net on port 465 with SSL. Turn on outgoing authentication (“My outgoing server requires authentication”) with the same settings as the incoming server.

What are the Suddenlink email settings?

IMAP imap.suddenlink.net on 993, POP3 pop.suddenlink.net on 995 and SMTP smtp.suddenlink.net on 465, all with SSL, and your full suddenlink.net address as the user name.

Does Optimum use port 587?

Optimum’s email FAQ lists only port 465 with SSL for outgoing mail. Use 465 and enable SSL in your mail app.

Can I still create an Optimum email account?

No. As of May 4, 2021, Optimum no longer lets new or existing Internet customers create new email accounts. Existing optimum.net addresses keep working.

Email validation API

Validate optimum.net addresses before you send

emailvalidation.io checks syntax, MX records and the mailbox over SMTP, flags disposable, role and free addresses and returns a quality score, in one request.

/v1/info Email validation API Read the documentation

100 free validations every month. No credit card required.

GET https://api.emailvalidation.io/v1/info?email=support@emailvalidation.io

{
  "email": "support@emailvalidation.io",
  "user": "support",
  "tag": "",
  "domain": "emailvalidation.io",
  "format_valid": true,
  "mx_found": true,
  "smtp_check": true,
  "catch_all": null,
  "role": true,
  "disposable": false,
  "free": false,
  "score": 0.64,
  "state": "deliverable",
  "reason": "valid_mailbox",
  "did_you_mean": ""
}

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