How to troubleshoot common email validation errors in Verifycatchall

If you're wrangling lists of emails and running them through Verifycatchall, you know the pain: weird errors, confusing results, and a lot of noise. This guide is for anyone who needs to actually get to the bottom of email validation errors—no fluff, no hand-waving, just practical steps to get things working.

Let's break down the most common issues, what causes them, and how to fix (or at least work around) them.

1. Know What Verifycatchall Can (and Can’t) Do

Before you start troubleshooting, it's worth a reality check. Verifycatchall is a tool built to help you figure out if an email address is valid, with a special focus on so-called "catch-all" domains. That means:

  • It tries to tell you if an email will bounce or not.
  • It can't guarantee 100% accuracy—especially with catch-all domains, where the server says every email is valid (even when it isn’t).
  • Results depend on external factors (like mail server responses, DNS records, and network issues).

What does this mean? Sometimes, the problem isn't you, or Verifycatchall—it's just how email works. Keep that in mind as you troubleshoot.

2. Step-by-Step: Troubleshooting Common Errors

Step 1: Start with the Basics

  • Check Your Input List
    Garbage in, garbage out. Make sure your emails are:
  • Properly formatted (no typos, extra spaces, missing "@" symbols)
  • One email per line (CSV or TXT works best)
  • No weird characters or accidental line breaks

Pro tip: Run your list through a simple regex check to weed out obvious formatting errors. Don’t trust Excel or Google Sheets to catch everything.

  • Test with a Known Good Email
    Use a personal Gmail or Outlook address you know is valid. If Verifycatchall throws an error here, there's something wrong beyond your list.

Step 2: Understand the Error Messages

Verifycatchall usually returns clear messages, but some need translation. Here are the ones you'll see most often:

a. "Catch-all Detected"

  • What it means: The domain’s mail server accepts all emails, whether they exist or not.
  • What to do:
  • You can’t know for sure if the email is deliverable.
  • If quality matters, consider extra verification (like a confirmation email).
  • Don’t bother chasing a “definitive” answer from any tool—nobody can give it.

b. "Invalid Email Syntax"

  • What it means: The address doesn't conform to standard email formatting.
  • What to do:
  • Check for typos, missing "@" or periods, illegal characters.
  • Use a linter or regex (^[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}$) for a quick scan.

c. "Mailbox Does Not Exist" or "No MX Records Found"

  • What it means: The domain isn’t set up to receive emails, or the address is outright fake.
  • What to do:
  • Double-check the spelling of the domain.
  • For brand-new domains, DNS records may need time to propagate (wait a few hours).
  • If it's a typo (e.g., "gamil.com" instead of "gmail.com"), fix it and try again.

d. "SMTP Timeout" or "Server Not Responding"

  • What it means: Verifycatchall tried to connect but got no response.
  • What to do:
  • Check your own internet connection and firewall.
  • Try again later—sometimes mail servers rate-limit or block too many requests.
  • If it happens only with certain domains (e.g., Microsoft, Yahoo), the server may be intentionally limiting lookups.

e. "Greylisted" or "Temporary Error"

  • What it means: The server is saying "try again later."
  • What to do:
  • Wait a few minutes and retry.
  • If it's a persistent issue, that domain may be protecting itself from automated checks.
  • There’s not much you can do—move on.

Step 3: Check Your Connection and Environment

  • VPNs and Proxies:
    Some mail servers block or rate-limit connections from known VPNs, cloud hosts, or proxies. If you’re running Verifycatchall from a cloud VM, try from a local machine instead.

  • Firewalls:
    Make sure outbound port 25 (SMTP) isn’t blocked. Some networks (especially on corporate or hotel WiFi) restrict this.

  • Rate Limits:
    If you’re checking lots of emails at once, slow down. Too many requests too quickly can get your IP flagged.

Step 4: Dig Into the Domain

If an error keeps popping up for a particular domain:

  • Use nslookup or dig to check MX records:
    Run nslookup -type=mx domain.com or dig mx domain.com in your terminal. No MX records? No email delivery possible.

  • Check domain reputation:
    If the domain is disposable (like mailinator.com) or known for abuse, many tools will just flag it.

  • Manual SMTP check (advanced):
    If you’re comfortable, use telnet domain.com 25 and try a manual handshake. This is fiddly, but it can tell you if the server is up or just blocking automated tools.

Step 5: Make Peace with Catch-All Domains

Here’s the honest truth: nobody can reliably verify if a specific email exists on a true catch-all domain. The server’s job is to say "yes" to everything, to keep spammers guessing.

  • Don’t waste time hunting for magic solutions here.
  • If you want to reach a real person, send a test email and see if it bounces.

What Works, What Doesn’t, and What to Ignore

  • Don’t trust anyone claiming “100% accuracy” on catch-all results.
    Not possible. Anyone selling that is selling snake oil.
  • Ignore “advanced AI verification” claims on email validation.
    Most of it is marketing fluff. The technical limits are the same for everyone.
  • Bulk validation?
    Break your lists into smaller chunks and pace uploads to avoid triggering rate limits or bans.
  • If your bounce rate is still high after cleaning, the problem is likely with old, stale lists—not with Verifycatchall.

Pro Tips for Fewer Headaches

  • Keep your lists fresh. Old lists = more bounces.
  • Always send a double opt-in or confirmation email to new subscribers.
  • Don’t buy email lists—most are garbage, no matter what the seller says.
  • If you need to validate tons of emails regularly, rotate your IP or use different environments to avoid throttling.

Wrapping Up: Keep It Simple

Email validation is messy and, honestly, a little bit of a cat-and-mouse game. Tools like Verifycatchall get you most of the way there, but they can’t bend the laws of how email servers work. Stick to the basics, don’t chase magic bullets, and iterate as you go. When in doubt, test, tweak, and move on—there’s always another batch to clean.