Email deliverability is a moving target. You might have the best content in the world, but if your emails end up in spam—or worse, bounce—you’re wasting your time. If you’re managing lists, running campaigns, or just tired of cleaning up after messy opt-ins, you need more than basic email verification. You need rules that fit your audience. This guide is for folks who want to use Usebouncer to set up custom email verification rules and actually see better deliverability, not just check a box.
Let’s cut through the noise and get real about what works, what’s snake oil, and how to take control of your email list quality.
Why Custom Rules Matter (and When They Don’t)
Most email verification tools will tell you they’re “AI-powered” or “enterprise-grade.” Ignore the buzzwords. The basics—checking if an email address is real, not disposable, and not a known spamtrap—are table stakes.
But here’s the catch: every business and audience is different.
- If you’re B2B, you might want to allow only work email domains.
- If you’re running a newsletter, you might be fine with Gmail, but not with disposable services.
- Maybe you get a lot of typos from mobile signups and want to auto-correct the most common ones.
- Or maybe you’re sick of role-based emails like “info@” and “support@” eating up your credits.
Custom rules let you decide what’s “good enough” for your brand, not just what’s technically deliverable.
When you don’t need custom rules:
If you’re working with a small, high-trust list or you just need to weed out obvious spam, the built-in settings are probably fine. Don’t over-complicate things.
Step 1: Get Familiar with Usebouncer’s Verification Options
Before you mess with custom rules, you need to know what’s already built in. Usebouncer checks:
- Format (is it a valid email address?)
- Domain (does the domain exist and accept mail?)
- Disposable/temporary addresses
- Role-based addresses (admin@, sales@, etc.)
- Blacklisted or risky domains
- Mailbox existence (does the inbox actually exist?)
You can run these checks through their web dashboard, API, or batch uploads. Most people start with a CSV list and get a quick report.
Pro tip:
Do a test run with a small batch before you put your whole list through Usebouncer. You don’t want to burn through credits on a mistake in your setup.
Step 2: Decide What “Clean” Means for Your Use Case
This is where most people screw up. There’s no universal “clean” list—just what works for your audience and your goals.
Ask yourself:
- Am I OK with free email addresses (Gmail, Yahoo), or do I want just business domains?
- Do I want to block role-based emails?
- Should I filter out certain countries or regions?
- Am I willing to risk a few false positives for a cleaner list?
- What’s my tolerance for “catch-all” domains (domains that accept any address, real or not)?
Write these down. Seriously. If you skip this, you’ll end up fiddling with settings forever.
Step 3: Build Your Custom Rules in Usebouncer
Here’s the meat of it. Usebouncer has a flexible rules engine, but you do need to know where to find it and how it works.
3.1. Accessing Custom Rules
- Log in to your Usebouncer dashboard.
- Go to “Settings” or “Verification Rules” (they sometimes change labels—look for anything with “rules” or “customization”).
- Look for “Custom Rules” or “Advanced Filters.” If you’re on a lower-tier plan, you might need to upgrade.
3.2. Types of Rules You Can Set
Depending on your plan, you can set rules to:
- Block specific domains (e.g., *@mailinator.com for disposables)
- Allow only certain domains (e.g., *@company.com if you want just employees)
- Block role-based emails (info@, sales@, etc.)
- Set risk thresholds (e.g., block if Usebouncer marks it “risky” or “unknown”)
- Custom regex patterns (for nerds who want to block emails with specific patterns)
- Geo-based rules (block or allow signups from certain countries)
Most of these are toggle switches or input boxes. You don’t have to be a developer, but if you want to get fancy, regex lets you do pretty much anything.
Examples:
- Block all disposable domains:
*@tempmail.com, *@mailinator.com, *@10minutemail.com - Allow only business domains:
Exclude all @gmail, @yahoo, @outlook, etc. - Block role-based addresses:
Enable the “Role-based” filter.
3.3. Rule Order Matters
If you create multiple rules, the order can affect what gets through. For example:
- Allow only business domains.
- Block role-based addresses.
- Exclude risky or unknown validation results.
Test your rules with sample addresses to see what slips through.
Step 4: Test, Test, and Test Again
Don’t trust that your rules are working just because you clicked “Save.” Usebouncer usually has a “Test” or “Preview” feature—use it.
- Upload a small sample list with different types of emails (real, fake, role-based, disposable, foreign domains, etc.).
- Check the results. Are you blocking legit users? Are obvious fakes getting through?
- Adjust your rules and re-test as needed. This is where most people catch edge cases they didn’t think of.
Pro tip:
Keep a spreadsheet of “weird cases” you encounter over time. Add those to your tests each time you update your rules.
Step 5: Integrate with Your Signup or Import Process
Once your rules are dialed in, make sure they’re actually being used where it matters:
- For new signups:
If you’re using Usebouncer’s API, plug your rules into your signup form validation. That way, bad emails never make it into your database. - For bulk imports:
Run every new batch through Usebouncer before you send a single campaign. - For ongoing hygiene:
Schedule periodic list cleaning (monthly, quarterly, whatever fits your volume).
Don’t just set it and forget it. Spammers, bots, and typo trends change over time. Revisit your rules every few months.
What to Ignore (and What to Watch Out For)
A few things people waste time on:
- Over-optimizing for zero bounces:
You’ll never hit 0%. Chasing it means you’ll block real people and hurt your list. - Blocking all free providers:
Sometimes, real people use Gmail or Outlook for work. Blocking these can cut your reach. - Chasing every new disposable domain:
Usebouncer’s database is pretty good. Don’t try to maintain your own blocklist unless you have a very specific problem. - Obsessing over “unknowns”:
Some domains just don’t play nice with verification tools. Unless you know they’re bad, don’t block them by default.
Pro Tips for Better Deliverability
- Set up good sending practices:
Even a perfect list won’t save you if your sending IPs are on blacklists or your emails look spammy. - Warm up new domains:
If you’re switching domains or sending from a new address, ramp up volume slowly. - Monitor feedback loops:
Keep an eye on spam complaints and unsubscribes. If you see a spike, review your list and rules. - Always have a “real people” override:
Sometimes, your rules will block someone important. Make it easy for legit folks to reach out if they can’t sign up.
Keep It Simple—Iterate as You Go
Perfect is the enemy of good here. Start with a few sensible rules, see what works, and tweak over time. Don’t get lost in the weeds trying to outsmart every spammer on day one. Use the tools, trust your gut, and remember: the goal is to reach real people, not to have a “clean” list for its own sake.
Happy sending.