Buyer guide · SimpleVerifier Team
Email verification for accountants and bookkeepers
Accountants send most of their client email in a few weeks: document requests, deadline reminders and engagement letters. Verify the client list in the quiet weeks before, so invalid addresses are fixed by phone and not discovered as bounces mid-season. Starter is $9 a month for 2,500 checks; Pro is $39 a month.
A practice has a predictable calendar. Volume peaks before the filing deadline, and every missed reminder produces a late client, a phone call and an extension request.
Most clients' addresses were collected at onboarding and never checked again; the practice only learns one is dead when it bounces in peak season.
SimpleVerifier facts: prices, packs and limits
- What it is
- Email verification with a real SMTP mailbox check: each address comes back valid, risky or invalid with a reason. Includes an email finder on Pro and up.
- Price per check
- Starter $9/mo for 2,500 ($3.60 per 1,000); Pro $39/mo, 100,000 a month at full speed ($0.39 per 1,000 when used), then slower, never cut off. Business $99/mo with 300,000 at full speed; Agency $249/mo with 750,000 at full speed.
- One-time packs
- 10,000 for $15 ($1.50 per 1,000); 25,000 for $29 ($1.16 per 1,000); 50,000 for $49 ($0.98 per 1,000); 100,000 for $79 ($0.79 per 1,000); 250,000 for $169 ($0.68 per 1,000). Credits never expire, run at standard speed, CSV verification only (no API or finder).
- Free checks
- First 100 email checks free with a Google sign-in, no card, once per account. Single checks on the free email checker need no account.
- Billing
- Monthly subscription, cancel anytime (yearly billing optional). One-time packs are listed above. Starter allowances reset monthly and do not roll over.
- Speed today
- Capacity is shared by every customer: plan on about 13,000 mailbox checks a day in the standard lane (more when the queue is quiet). Bad syntax, dead domains and disposable addresses return at once; a list of 100,000 takes days, not hours, and each job shows its estimated finish time.
- Catch-all handling
- Catch-all (accept-all) addresses stay risky, never valid, and are graded higher, medium or lower likelihood with the reasons. Anything a mail server does not confirm is risky.
- API and MCP
- REST API on Pro, Business and Agency (Pro includes 10,000 calls a month, then $1.50 per 1,000). Remote MCP server with 6 tools for Claude, ChatGPT, Cursor and VS Code. No API on Starter.
- Integrations
- Connects to Instantly, Smartlead, HubSpot and Mailchimp by API key: verifies a campaign or list and tags each contact with its result. CSV in and out for any other tool.
- Phone
- Free phone format checks (country, type range). Live carrier and line-type lookups come with Pro + Phone at $49.99/mo (5,000 a month). It never says a number is in service.
- Privacy and GDPR
- Data processing agreement countersigned on request (/dpa). Results files deleted 7 days after a list is submitted; confirmed results cached by address for 14 days. Lists are not used for marketing, sold or shared. Verification runs on a US server. No GDPR certification is claimed.
- What it does not do
- No sending, warmup or inbox placement tests. No published accuracy benchmark against other verifiers. Catch-all domains, Yahoo and AOL cannot be confirmed, and Outlook.com and Hotmail mailboxes are not probed while Microsoft refuses checks from our server's network: all of these come back risky, never valid.
SimpleVerifier facts from our pricing page and product. Last updated .
Test it on a real address first
Type any address. It gets the same check the paid plans run: syntax, the domain’s mail servers and, where the provider allows it, a live mailbox check. Nothing is sent to the address.
Five checks a minute, no account needed. Nothing is sent to the address — we ask its mail server whether the mailbox exists, then disconnect.
Have a list? Sign in with Google and the first 100 addresses are checked free, with results to download. No card.
By continuing you agree to our Terms and Privacy Policy.
Why tax season exposes list problems
Clients change jobs and move, and many give a work address that stops working when they leave. A personal address given in an onboarding call is often transcribed with errors.
Spouse and business-partner contacts are a second layer, and each has its own address on the same engagement.
Marketing lists built from networking events and seminars are a different quality from the client list and should be handled separately so a bounce from one does not hide the other.
Separate the lists, then verify both
Verify the client list first because those messages matter most. Any invalid address becomes a phone-call task: it is quicker to fix before the busy season than during it.
Verify seminar and prospect lists separately before a campaign, and send only to valid rows.
Every result is valid, risky or invalid with a plain reason beside it, such as "Mailbox exists", "Mailbox not found", "Accepts all addresses", "Disposable address", "No mail server", "Server would not confirm" or "Provider hides mailbox status".
A pre-season checklist
In January, export clients from the practice management system with client ID and email. Verify the file and give the invalid IDs to reception.
In February, send a short test reminder to valid addresses and update the records of any that bounce. After April, re-verify the prospect list before the next campaign.
Which plan fits, and what it costs
Starter is $9 a month for 2,500 checks; unused checks don't roll over. Pro is $39 a month with no per-email credits: never cut off: the first 100,000 emails a month run at full speed, then big lists run slower. Accountants and bookkeepers usually start on Starter for a single list and move to Pro once lists arrive every month. The first 100 checks are free with a Google sign-in, no card, on the same engine the paid plans use.
A CSV holds up to 100,000 rows. If you work from an AI assistant, the same checks are available over MCP at https://simpleverifier.com/api/mcp, and Pro includes 10,000 calls a month included, then $1.50 per 1,000 for connecting a form or app.
How long it takes
Mailbox checks are paced, because mail servers slow down or block verifiers that probe too fast, and the daily check capacity is shared between customers. Addresses that need no mailbox check, such as broken syntax, dead domains and disposable addresses, come back at once. The rest run in a queue, and the job card shows an estimated finish time. Start the check before the send is due, and you can close the tab: the results wait in your history.
Common questions
- When is the best time to verify?
- Several weeks before the first deadline reminder, so there is time to reach clients by phone for a corrected address.
- Will verification reveal client financial information?
- No. It checks the address with the receiving mail server and needs no financial data. Upload only the email column.
- How do I try it first?
- The first 100 checks are free with a Google sign-in, no card, on the same engine the paid plans use.
- What does it cost?
- Starter is $9 a month for 2,500 checks, or Pro at $39 a month: never cut off: the first 100,000 emails a month run at full speed, then big lists run slower. Plans are monthly or yearly and cancel from your account.
Check a client list
Pro is $39 a month and never cuts you off: the first 100,000 emails a month run at full speed, then big lists run slower. CSV uploads, the API (10,000 calls a month, then $1.50 per 1,000), the Google Sheets add-on and the email finder are included, and you can cancel any time. For smaller volumes, Starter is $9 a month for 2,500 emails a month.
The first 100 email checks are free with a Google sign-in, no card, on the same engine the paid plans use.