Email List Hygiene for Real Estate Agents: Leads and Sphere

A real estate agent's email list is really three lists with different problems: new portal and website leads (typos and fake sign-ups), the sphere and past clients (addresses collected years ago), and old ISP addresses like aol.com and att.net that are now hosted by Yahoo. Each needs a different cleaning step, done at a different time.

Most list-cleaning advice treats a list as one file. In real estate that misses where the bad addresses actually come from.

Where real estate email addresses come from

The source of an address predicts how it fails. Portal and IDX leads fail at entry; sphere addresses fail through age; ISP addresses fail because the provider behind them changed.

Source	Typical age	Main failure	When to verify
Portal leads (Zillow, Realtor.com, Homes.com)	Days	Typos, throwaway addresses	As they land in the CRM
IDX website registrations	Days to months	Fake addresses typed to get past a sign-up wall	As they land, then before nurture campaigns
Open house sign-in sheets	Days	Handwriting transcription errors	Same day, while you can still ask
Sphere of influence	Years	Abandoned or retired mailboxes	Before every large send
Past clients	Often 5-15 years	Same as sphere, plus ISP changes	Before anniversary and market-report sends

New leads: the fake address problem

Website and portal leads should be verified the moment they arrive, because a bad one enters an automated campaign immediately. Most agent CRMs start a drip or action plan as soon as a lead is created.

The fake-address problem is worst on IDX sites that require registration to view listings. People who only want to browse type whatever gets them past the form. The trade-off is real: in a 2018 test on JB Goodwin REALTORS' site, Real Estate Webmasters reported roughly 65 leads a week with forced registration switched on, against about 5 a week with it off. Forced registration gets you far more leads, and a larger share of them are not real.

You do not have to choose between volume and quality. Keep the registration wall if it works for you, and check each address as it is captured:

• Syntax and typo check catches gmial.com, missing dots and spaces. See catching email typos at signup.
• Disposable domain check catches throwaway inboxes, which a sign-up wall attracts. Our disposable email checker is free.
• Mailbox check confirms the address actually exists. Run a single address through the free verifier to see what this returns.

A lead with a fake email is not always a fake lead. Plenty of people give a real phone number and a junk email, or the reverse. Flag the email as bad, and let the phone number decide whether the lead is worth a call.

What your CRM does after a bounce

CRMs record bounces after they happen; they do not stop the first one. Follow Up Boss, for example, tags a contact bounced when certain emails bounce, including drip campaign emails, and shows the bounced email in orange on the timeline (Follow Up Boss help). BoldTrail (formerly kvCORE) sorts contacts into statuses including New Lead, Active Lead, Sphere and Archive, and moving a contact to Archive unsubscribes them from further automated communication (BoldTrail help).

Both are useful for clean-up. Neither prevents the bounce, and every bounce counts against the domain you send from. Verification sits in front of the CRM and stops the address before the first email.

The sphere: addresses collected years ago

Sphere and past-client lists decay through age, so verify them before every large send, not once. This is the list that matters most to an agent's business, and it is usually the oldest.

The numbers explain why. In NAR's 2025 Profile of Home Buyers and Sellers, 43% of buyers found their agent through a referral from a friend, neighbour or relative, and 18% of repeat buyers used an agent they had worked with before. The same report puts the typical seller's time in their home at a record 11 years (NAR summary; the referral figures are from the full report, chapter 4).

Put those together. The past client you most want to hear from may be someone whose email you collected at a closing a decade ago. In that time people abandon inboxes, leave employers (if you saved a work address), and lose ISP accounts when they change broadband provider.

A sphere list fails in a particular way: most addresses are fine, and a minority are dead. A send to the whole list without checking still produces enough hard bounces to hurt deliverability for the next market update, the next listing announcement, and every one-to-one email from the same domain.

The fix:

1. Export the sphere and past-client segments from your CRM as CSV.
2. Run them through a verifier before your next newsletter or market report.
3. Mark invalid addresses as bad in the CRM (do not delete the contact).
4. Send to valid addresses as normal; send risky ones separately and in smaller batches.
5. For invalid past clients, ask for a new address by phone or text. A short "updating my records" message is a perfectly natural reason to call.

Old ISP addresses now live at Yahoo

Many addresses in long-held real estate lists are on old internet-provider domains, and a lot of those now route to Yahoo's mail servers. That matters because Yahoo is one of the providers whose mailbox status is hardest to confirm without sending. We cover the mechanics in why Yahoo addresses are hard to verify.

We looked up the MX records (the servers that accept mail for a domain) of common legacy ISP domains on 1 October 2026 using dig MX. The raw output is saved with our research notes.

Domain	Mail currently handled by
aol.com	Yahoo (mx-aol.mail.gm0.yahoodns.net)
verizon.net	Yahoo (same AOL servers)
att.net, sbcglobal.net, bellsouth.net	Yahoo (mx-att.mail.am0.yahoodns.net)
cox.net	Yahoo (mta5-7.am0.yahoodns.net)
frontier.com, frontiernet.net	Yahoo (mta5-7.am0.yahoodns.net)
comcast.net	Comcast's own servers
charter.net, roadrunner.com, twc.com	Charter's own servers
earthlink.net	EarthLink (filtered by Vade Secure)
juno.com, netzero.net	United Online servers

Cox's move is recent: Spam Resource reported that the cox.net MX record switched to Yahoo in October 2024.

What this means in practice:

• An old @verizon.net or @sbcglobal.net address on your list is checked against Yahoo, not the original provider.
• Expect more risky results on these domains than on Gmail. Risky means the check could not confirm the mailbox either way, not that the address is bad.
• Treat a batch of risky ISP addresses as its own segment: send to it separately, smaller, and watch the bounces.

If someone changed broadband provider years ago, their old ISP address may have been retired with the account. That is the classic way a sphere address dies, and it is invisible until you check or bounce.

Open house sign-in sheets

Paper and tablet sign-in sheets produce transcription errors, so verify them the same day while you can still fix them. Handwritten addresses are misread when typed up later, and visitors on a shared tablet often mistype on the small keyboard.

The window to correct a bad address is short. If you verify on the evening of the open house and find jsmith@gmal.com, you can fix it before the follow-up goes out, or call the number on the same line. A week later, you have a bounce and a lead who never heard from you.

Rules that apply to all three lists

CAN-SPAM applies to marketing email from agents just as it does to any business. The FTC's compliance guide requires a working opt-out honoured within 10 business days, an accurate sender and a physical postal address. Verification does not change any of that; it only stops you sending to addresses that cannot receive mail. This is not legal advice.

Three habits keep real estate lists healthy:

• Never delete a contact because their email failed. Mark the email bad and keep the person. Real estate relationships run for years, and the phone number may still work.
• Do not send market reports from a brand-new domain to an unverified sphere. If you are moving to a new brokerage domain, check your SPF, DKIM and DMARC first with the deliverability audit, and verify the list before the first send.
• Keep portal leads and sphere in separate segments. Their bounce risk is different, and mixing them hides which source is causing problems.

A cleaning schedule for an agent's database

Verify new leads on arrival, the sphere before each large send, and the whole database once a year.

When	What to verify	Action on invalid
Every new lead (automated or daily)	Portal, IDX and open house leads	Flag email bad; call or text instead
Before each newsletter or market report	Sphere and past-client segments	Mark bad; ask for a new address
Annually	Whole database	Archive dead emails; review risky segment
When changing brokerage or domain	Everything, before the first send	Fix authentication first, then verify

The practical takeaway: your sphere is your business, and it is also your oldest and least-checked list. Verify it before the next market update rather than after the bounces arrive, and keep the people even when you drop their addresses.