Catching bad email addresses before you invoice
Catching a bad email address before you send an invoice takes three checks: that it is well formed, that its domain has a mail server, and that it doesn't belong to a disposable mail service. That catches most typos, but no outside check proves a person reads the mailbox.
An invoice sent to the wrong address doesn't bounce loudly. Sometimes it vanishes, sometimes a bounce lands in a mailbox nobody watches, and the earliest sign of trouble is a payment that never comes. A minute spent checking an address when you add a customer saves a reminder and an awkward phone call later.
Four ways an email address goes wrong
| Problem | Example | Can a check catch it? |
|---|---|---|
| Badly formed | A missing @, a space, two dots in a row | Yes, from the text alone |
| No mail server for the domain | A typo in the domain, such as a misspelled company name | Yes, with a DNS lookup |
| Disposable address | A throwaway mailbox that expires | Usually, against a list of known services |
| Wrong person or dead mailbox | A former employee, a misspelled name before the @ | No, not from outside |
What each check tells you
Syntax
The cheapest check reads the address itself: one @, something before it, a domain with at least one dot after it, no spaces. It catches pasting accidents and half-typed addresses, and nothing more.
Mail server (MX) lookup
Most domains that receive email publish mail server records, called MX records, in the DNS. Looking them up tells you whether the domain can receive mail at all. A domain with no MX record is usually a typo, or a company that no longer uses that domain.
Disposable domains
Some services hand out throwaway addresses that stop working after a short time. They are fine for a newsletter sign-up, but a customer record that carries one is worth a question. A good check flags them rather than rejecting them, because a real customer may have a reason.
The part no outside check covers
An address can pass every check above and still go nowhere: the person left, the mailbox is full, or one letter before the @ is wrong. Many mail servers accept mail for unknown recipients or hide whether a mailbox exists, so no outside lookup proves it. A reply, or a confirmation from the customer, does.
A habit that catches most mistakes
- Check when the record is created. That is when the person who knows the customer is still at hand.
- Prefer a shared billing address. Ask business customers for an accounts address rather than one person's mailbox, so invoices survive staff changes.
- Treat a flag as a question. A disposable or unreachable address is a reason to ask, not to delete the customer.
- Re-check after a bounce. If an invoice email comes back, fix the address on the record, not just in the reply.
- Clean old lists before you import. The guide to cleaning data before an import covers emails along with duplicates and missing values.
A correct email address is one part of a clean customer record. A valid VAT number is another: see how to check an EU VAT number with VIES. For how customers, contacts and addresses fit together, see structuring B2B customer data, and for more ways to shorten the wait for payment, getting paid faster.
How it works in Swiftly Workspace
In Swiftly Workspace, the Email field of a customer, a vendor, a customer contact and a vendor contact has a Verify button next to it, on Mac and on iPhone and iPad.
- After the record is saved. Verify appears once the record exists. Email checking is on unless an admin turns it off.
- What it checks. The address's format, whether its domain has a mail server, and whether the domain is a known disposable service.
- What the badge says. Valid, with the date it was verified. Valid · flagged disposable when the domain is a throwaway service: a warning, not an error. Invalid with a short reason when the domain has no mail server. Not verified before a check, or when the address isn't shaped like an email address.
- Fresh, not forever. A result is kept for seven days. After that, or when you change the address, the badge shows Re-verify.
- Honest about outages. When the lookup can't be completed, the badge says the service is unavailable and to try later, instead of calling the address invalid.
- Advice, not a gate. The check never stops you saving a record. You decide what to do with a flag.
Like any outside check, it confirms the domain can receive mail, not that the person reads it.
Frequently asked questions
Can I find out if an email address exists without sending a message?
Not reliably. You can confirm the address is well formed and that its domain has a mail server. Whether the mailbox itself exists is something many mail servers won't reveal, so a reply or a confirmation from the customer is the real proof.
What is an MX record?
A DNS record that names the mail servers for a domain. If a domain has none, mail to it will very likely fail.
Should I refuse customers who use a disposable email address?
Usually not. Treat it as a question: ask for a lasting address for invoices, and keep the customer either way. A flag is information, not a verdict.
When should I re-check a customer's email address?
Whenever an address changes or an email bounces, and as part of any clean-up before an import. Domains do expire, so an occasional pass over long-standing customers is worthwhile too.
Run your business on Apple.
Create your account on the web, then set up your workspace in the app on your iPhone, iPad or Mac.
Create your account
