att.net, verizon.net and sbcglobal.net Addresses: Should You Keep Them in Your List?

Keep att.net, verizon.net and sbcglobal.net addresses that engaged recently, and send to the rest in a small, separate batch. These old internet-provider domains still receive mail, but most of them now run on Yahoo's servers, which accept any address during a verification check. So no verifier can confirm them: an honest one marks them risky, not valid or invalid. Deleting them all throws away real customers; sending to all of them at once risks a bounce spike. Find them in your list with the bulk email provider lookup.

See who hosts each address in your list →

Who runs these domains' mail now

We looked up the MX record (the server that receives mail) for common internet-provider domains on 9 November 2026:

Domain	First MX record	Runs on
att.net	mx-att.mail.am0.yahoodns.net	Yahoo
sbcglobal.net	mx-att.mail.am0.yahoodns.net	Yahoo
bellsouth.net	mx-att.mail.am0.yahoodns.net	Yahoo
pacbell.net, ameritech.net, prodigy.net, swbell.net, flash.net	mx-att.mail.am0.yahoodns.net	Yahoo
verizon.net	mx-aol.mail.gm0.yahoodns.net	Yahoo (same as aol.com)
cox.net	mta5.am0.yahoodns.net	Yahoo
frontier.com, frontiernet.net	mta5.am0.yahoodns.net	Yahoo
rogers.com (Canada)	mx-rogers.mail.am0.yahoodns.net	Yahoo
sky.com (UK)	mx-eu.mail.am0.yahoodns.net	Yahoo
comcast.net	mx1.mxge.comcast.net	Comcast's own
charter.net, spectrum.net	mx0.charter.net	Charter's own
earthlink.net	mx01.earthlink-vadesecure.net	A hosted filtering service
centurylink.net	mx.centurylink.net	CenturyLink's own
optonline.net	mx.altice.prod.cloud.openwave.ai	Hosted mail platform
juno.com, netzero.net	mx.dca.untd.com	Shared own servers (untd.com)

You can repeat this yourself:

for d in att.net sbcglobal.net verizon.net cox.net comcast.net; do
  echo "$d $(dig +short mx $d | sort -n | head -1)"
done

MX records can change, so check again before you rely on the table.

Why a verifier can't confirm them

An email verifier asks the recipient's mail server whether a mailbox exists, without sending a message. That only works if the server says no to addresses that don't exist.

Yahoo's servers don't. In our mailbox provider study in October 2026, yahoo.com, aol.com and the ISP domains Yahoo hosts (att.net, sbcglobal.net, cox.net, sky.com, rogers.com) accepted a made-up address in both rounds. Yahoo reports unknown users after a message is sent instead. Why Yahoo addresses are hard to verify explains the SMTP detail.

So for every address on these domains, the honest answer is risky: the server is reachable, but it can't tell you whether the mailbox is real. If a tool marks a made-up att.net address as valid, it has told you something about the tool, not the address.

Comcast is different but not easier. In the same study, Comcast refused our check at the connection stage, so its addresses also came back risky. That says something about how Comcast judges checking servers, not about the mailboxes.

What's actually wrong with old ISP addresses

These addresses are not bad by nature. Many people have used the same att.net or verizon.net address for twenty years. The risks are:

• Abandoned inboxes. People switch providers or move to Gmail and stop reading the old address. Yahoo's help pages say a mailbox not accessed for 12 months becomes inactive and stops receiving mail.
• No confirmation. You can't sort live ones from dead ones with a check.
• Strict filtering. Mail to these domains goes through Yahoo's servers, so expect the same filtering you see at yahoo.com. See Gmail and Yahoo bulk sender requirements.

How to handle them, step by step

1. Find them

Upload your list to the bulk email provider lookup. It shows the mail host for each address, so all the Yahoo-hosted ISP domains group together. You can also use the free vs business email filter to separate consumer addresses from company ones.

2. Verify the whole list anyway

ISP addresses will come back risky, but verification still removes:

• Syntax errors and typos (like att.nett or sbcgloabl.net). The email typo corrector fixes the common ones first.
• Domains with no mail server at all. If a domain in your list no longer receives mail, its addresses come back invalid.
• Duplicates. The duplicate email remover handles them before you upload.

Upload at /verify and download valid, risky and invalid separately.

3. Split the risky group by engagement

This is the step that matters. From your email platform, export opens, clicks or purchases for the last 6 to 12 months.

Group	What to do
ISP address, engaged recently	Keep in your normal sends; the inbox is clearly alive
ISP address, no engagement in 12 months	Send a small re-permission batch first
ISP address, never engaged	Consider removing; at minimum, send last and watch bounces

Note that opens are not reliable on their own because of privacy features in some mail apps. Clicks and purchases are better signals.

4. Send the re-permission batch slowly

1. Pick a small slice, a few hundred addresses.
2. Send a short, plain email asking if they still want to hear from you.
3. Remove anything that hard bounces. A hard bounce from Yahoo for an unknown user is permanent; see hard bounce vs soft bounce.
4. Check your bounce rate with the bounce rate calculator. If it is low, send the next slice.

Mailing an old email list covers re-permission campaigns in more detail.

5. Suppress what bounced

Pull the bounced addresses from your platform's report with the bounced email extractor and add them to your suppression list.

Who has the most of these addresses

Lists with a lot of ISP addresses tend to be:

• Older consumer lists: retail, travel, local services.
• Real estate and mortgage leads, where many contacts signed up years ago.
• Nonprofit donor lists.
• Alumni and membership lists.

If your list is mostly B2B leads, ISP addresses are usually a sign of personal emails mixed in. See personal emails in a B2B lead list.

Choosing a verifier for a consumer list

If your list is full of ISP and Yahoo addresses, judge verifiers on honesty, not on how many addresses they call valid. A quick test:

1. Make up an address that can't exist at att.net, such as a long random string.
2. Make up one at gmail.com the same way.
3. Run both through the tool.

The right answers are risky for att.net and invalid for gmail.com. A tool that calls both valid will tell you your whole consumer list is fine, and your first campaign will prove it wrong. Our guide on how to tell if your email verifier is lying has more tests like this.

On a list like this, expect a large risky share. That is the honest outcome for these domains, not a weak result.

Quick answers

• Is verizon.net still a working email domain? Yes, its MX record pointed at Yahoo's servers on 9 November 2026.
• Does a risky result mean the address is bad? No. It means it can't be confirmed either way.
• Can a different verifier confirm att.net addresses? Not with a standard mailbox check, because Yahoo's servers accept every address. Be wary of any tool that says valid for all of them.

Check your list

Upload your list at /verify. The first 100 checks are free with a Google sign-in, no card. You'll see exactly how many of your addresses sit on Yahoo-hosted ISP domains.

Pro, $39 a month: Unlimited email verification.* Never metered, never cut off. See pricing.

*Fair use: the first 100,000 checks a month at full speed, then slower, never cut off.

More: Yahoo email domains, business email vs personal email, accept-all vs unknown results.