I can't send email
Turn on "My outgoing server requires authentication" and "use same settings as incoming", and use mail.optimum.net, port 465, SSL on.
Optimum Email: Settings, Sign-In & Fixes
Optimum (Altice USA) looks after old Optimum Online and Suddenlink addresses, but Suddenlink addresses use their own server names. Optimum pages also disagree on the username, so try the full address first.
Covers @optonline.net, @optimum.net, @suddenlink.net. Run by Altice USA (Optimum). Checked against Optimum's own help pages, November 2026.
⚠️ Existing addresses keep working; no new sign-ups
Optimum stopped creating new email addresses on May 4, 2021. Existing optonline.net, optimum.net and suddenlink.net addresses keep working.
Optimum email server settings
| Server | Address | Port | Security |
|---|---|---|---|
| Incoming (IMAP) | mail.optimum.net | 993 | SSL/TLS |
| Incoming (POP) | mail.optimum.net | 995 | SSL/TLS |
| Outgoing (SMTP) | mail.optimum.net | 465 | SSL/TLS |
- Username: Your full email address. If that is rejected, try your Optimum ID (the part before the @). Suddenlink addresses use imap.suddenlink.net, pop.suddenlink.net and smtp.suddenlink.net instead.
- Use IMAP if you read mail on more than one device; POP downloads mail to one device only.
Official page: Optimum email settings
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Common Optimum email problems
My mail app rejects my login
Try your full email address as the username. If that fails, try just your Optimum ID, the part before the @.
My Suddenlink address won't connect with the Optimum servers
Suddenlink has its own servers: imap.suddenlink.net (port 993), pop.suddenlink.net (port 995) and smtp.suddenlink.net (port 465), all with SSL on.
My old setup on ports 143, 110 or 587 stopped working
Switch to the secure ports with SSL on: 993 for IMAP, 995 for POP and 465 for outgoing mail.
I want a new Optimum email address
Optimum no longer creates new addresses. Use a free provider such as Gmail or Outlook.com instead.
Problems that look the same on every provider
Can't sign in, or the password stopped working
- Sign in on the provider's own webmail page first. If that works, the problem is your mail app, not the account.
- If webmail rejects the password, use the provider's "Forgot password" page. Never use a reset link from an email you did not ask for.
- Many providers now need a separate app password (or their own sign-in screen) for Outlook, Apple Mail and phone apps. Your normal password will not work there.
Not receiving emails
- Check Spam, Junk and any filters or "blocked senders" in webmail.
- Check whether the mailbox is full; most providers stop accepting mail at the storage limit.
- If your app shows nothing new but webmail does, remove and re-add the account in the app using IMAP.
Can't send, or emails are stuck in the Outbox
- Check the outgoing (SMTP) server, port and security on this page against your app; old guides often list ports that no longer work.
- Turn on "My outgoing server requires authentication" and use the same username and password as incoming.
- Large attachments are a common cause. Remove the attachment and try again.
Contacts are getting spam from my address
- Change the password from webmail, then sign out of all other sessions if the provider offers it.
- Check forwarding rules, filters and the reply-to address in settings; attackers often add a hidden forward.
- Turn on two-step verification, and update the password anywhere else you used the same one.
Setting it up on a new phone or computer
- Use IMAP rather than POP so mail stays in sync across your phone, computer and webmail.
- Enter your full email address as the username unless the provider says otherwise.
- If the app offers the provider by name (Yahoo, Google, Outlook), choose that instead of "Other".
Sources: Optimum: using Optimum or Suddenlink email in an email program · Optimum: email server settings (IMAP and POP) · Optimum: fixing common Optimum email problems. Providers change settings from time to time; their own page is the final word.
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