Cox SMTP Settings
Cox.net mailboxes, run by Yahoo Mail since Cox handed the service over in 2025.
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Outgoing mail (SMTP)
SMTP server
smtp.mail.yahoo.com
Port. STARTTLS
587
Port. SSL/TLS
465
Security
SSL/TLS on 465 (recommended) or STARTTLS on 587. Cox mail now runs on Yahoo.
Incoming mail (IMAP)
IMAP server
imap.mail.yahoo.com
Port. SSL/TLS
993
Incoming mail (POP3)
POP3 server
pop.mail.yahoo.com
Port. SSL/TLS
995
Sending limits & login
Daily send limit
About 500 emails per day (Yahoo Mail limits).
Authentication
Requires a Yahoo app password: Cox moved @cox.net mailboxes to Yahoo Mail, so the old Cox password and servers no longer work.
App password
Generate one at login.yahoo.com > Account Security > Generate app password.
The old smtp.cox.net and pop.cox.net servers were retired when Cox handed email over to Yahoo in 2024. Use the Yahoo servers above.
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Cox SMTP, IMAP and POP3 settings
Cox no longer runs its own email. Cox moved every cox.net mailbox to Yahoo Mail and says the switch finished in early 2025, so the address is unchanged but the servers are Yahoo's and the old pop.cox.net and smtp.cox.net hosts are no longer the mail path. Cox stopped letting anyone create new Cox Email accounts back on 15 August 2019.
For incoming mail, use the IMAP server imap.mail.yahoo.com on port 993, or POP3 at pop.mail.yahoo.com on port 995. Pick the exact values from the tool above and copy them straight into your mail client.
Checked against Cox's own documentation: cox.com, help.yahoo.com. Ports and limits change, so check there too if something will not connect.
Cox settings at a glance
One card with every server and port on it. Right click to save it, or share the page and this is the preview people see.
What to enter as your Cox username and password
Wrong credentials, not a wrong port, are the usual reason a Cox connection fails. These are the exact values to type.
Your full cox.net address, for example name@cox.net
A Yahoo app password generated on the Yahoo Account Security page, not your old Cox password
Get your app passwordHow to set up Cox in a mail client
The exact path through Cox's own settings, in order.
- 1
Sign in to Yahoo Mail once with your cox.net address
Go to mail.yahoo.com and sign in with the full address including @cox.net and the password created during the move, and accept Yahoo's terms.
- 2
Generate a Yahoo app password
At https://login.yahoo.com/account/security find the "External connections" section, click Create app password, type a name for the app and click Generate password.
- 3
Replace the incoming server with Yahoo's
IMAP is imap.mail.yahoo.com on port 993 with SSL/TLS. For POP use pop.mail.yahoo.com on port 995 with the encrypted connection box ticked.
- 4
Replace the outgoing server with Yahoo's
smtp.mail.yahoo.com on port 465 with SSL/TLS in Outlook, or port 587 with TLS in Mail on Mac, with outgoing authentication turned on.
- 5
Keep the cox.net address as the username
The username stays name@cox.net in both the incoming and outgoing sections. Only the servers and the password change, and the password is the app password.
- 6
Repeat on every device
Cox says the new settings have to be applied on each phone, tablet and computer separately, though you only do the Yahoo Mail setup itself once.
What Cox looks like filled in
Every mail client asks for the same handful of fields. Here they are with Cox's values already in place.
Account settings: Cox
Server
smtp.mail.yahoo.comPort
465Encryption
SSL/TLSAuthentication
RequiredUsername
Your full cox.net address, for example name@cox.netPassword
A Yahoo app password generated on the Yahoo Account Security page, not your old Cox passwordServer
imap.mail.yahoo.comPort
993Encryption
SSL/TLSAn illustration of the fields, not a screenshot of any one app. Field names differ slightly between Outlook, Apple Mail and Thunderbird; the values do not.
Cox SMTP settings in Thunderbird
The outgoing server dialog with Cox's details entered. Outlook and Apple Mail ask for the same four things under slightly different names.
Which port should you use for Cox?
SSL/TLS on 465 (recommended) or STARTTLS on 587. Cox mail now runs on Yahoo.
STARTTLS
Starts as a plain connection, then upgrades to an encrypted one. The modern standard for sending.
SSL/TLS
Encrypted from the first byte. Widely supported and a good choice when 587 is blocked.
Plain SMTP
Meant for server-to-server relay. Home networks and cloud hosts block it, so do not use it to send from a client.
Why your Cox connection is failing
The failures people actually hit with Cox, and what fixes each one.
The mailbox moved to Yahoo. Change the incoming server to imap.mail.yahoo.com and the outgoing server to smtp.mail.yahoo.com, and swap the stored password for a Yahoo app password.
Those hosts are no longer the mail path for cox.net addresses. Yahoo's cox.net article tells you to replace any existing outgoing server settings with smtp.mail.yahoo.com.
A cox.net account on Yahoo needs an app password in third-party clients, never the account password. Generate one at login.yahoo.com/account/security and paste that in.
Cox says the cox.net address is supported by Yahoo only once you sign in to Yahoo Mail and accept Yahoo's Terms of Service and Privacy Policy. Do that in a browser first, then fix the client.
Cox states it no longer manages or supports email after the transition and directs cox.net users to Yahoo at help.yahoo.com. Cox still handles internet, TV and billing.
Cox sending limits
cox.net mailboxes run on Yahoo Mail now, and Yahoo states it does not disclose how many recipients or messages can be sent at one time.
Max attachment
25 MB of attachments per message, the Yahoo Mail limit that now governs cox.net
Cox quirks by mail client
Outlook
Yahoo's cox.net instructions use File then Account Settings then Repair with "Let me repair my account manually" ticked, and give port 465 for the outgoing server.
Apple Mail
Untick "Automatically manage connection settings" first; Yahoo's cox.net steps give port 587 for smtp.mail.yahoo.com in Mail on Mac, not 465.
Sending cold email through Cox
About 500 emails per day (Yahoo Mail limits). Requires a Yahoo app password: Cox moved @cox.net mailboxes to Yahoo Mail, so the old Cox password and servers no longer work.
Those caps make single-mailbox sending fine for personal mail but a poor fit for cold outreach at volume. Emailchaser spreads sending across warmed inboxes and manages deliverability, so you can scale without burning Cox accounts.
Other internet provider (isp) email
Setting up more than one mailbox? These sit in the same category as Cox.
Common questions about Cox SMTP settings
What are Cox's SMTP settings?
Cox's outgoing (SMTP) server is smtp.mail.yahoo.com. Use port 587 (STARTTLS) or 465 (SSL/TLS). SSL/TLS on 465 (recommended) or STARTTLS on 587. Cox mail now runs on Yahoo. Sign in with your full email address and password (or app password).
What is Cox's IMAP or POP3 server?
Cox's incoming IMAP server is imap.mail.yahoo.com on port 993 (SSL/TLS). If you prefer POP3, use pop.mail.yahoo.com on port 995.
Which port should I use for Cox?
Use port 587 with STARTTLS wherever it's offered, it's the modern standard for authenticated sending. Port 465 with SSL/TLS is a solid alternative. Avoid port 25, which most networks block for client sending. Cox's recommended value is above.
Why won't my Cox SMTP connection work?
Check authentication first: Requires a Yahoo app password: Cox moved @cox.net mailboxes to Yahoo Mail, so the old Cox password and servers no longer work. Generate one at login.yahoo.com > Account Security > Generate app password. Then confirm the host, port and security method match exactly, a 587/SSL or 465/STARTTLS mismatch will fail to connect.
Can I send bulk or cold email through Cox?
Not at scale. About 500 emails per day (Yahoo Mail limits). Providers throttle bursts to fight spam, so pushing cold email through one mailbox hits limits and wrecks deliverability. High-volume outreach belongs on dedicated infrastructure that spreads sending across warmed inboxes, which is what Emailchaser does.
Do I lose my cox.net address if I cancel Cox internet?
No, as long as you completed the move. Cox says that once the transition to Yahoo Mail is finished and you have accepted Yahoo's Terms of Service and Privacy Policy, the cox.net address is supported by Yahoo and stays accessible even if you discontinue Cox service.
Which outgoing port do I use for a cox.net account, 465 or 587?
Yahoo's own cox.net guide gives 465 with SSL/TLS for Outlook and 587 with TLS for Mail on Mac. Both reach smtp.mail.yahoo.com. If sending fails on one, switch to the other and keep outgoing authentication turned on.
Can I still create a new cox.net email address?
No. Cox stopped offering new Cox Email accounts to new and existing internet customers on 15 August 2019, and the service has since moved to Yahoo. Existing cox.net addresses created before that date still work; for a new mailbox you would sign up for an ordinary Yahoo account.
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