Mailgun Email
Verification Integration
Connect your Mailgun account to ValidEmailChecker and verify your mailing lists without manual exports. Keep your transactional and marketing email lists clean, your sender reputation protected, and your bounce rates low — with support for both US and EU regions.
Connect Mailgun
Enter your API key to get started
Connection Name
Mailgun API Key
Where to find: Profile → API Security → Create Key → Copy API Key
What You Need to Get Started
Mailgun Account
Active account with API access.
Private API Key
Profile → API Security.
Verification Credits
1 credit per email verified.
60 Seconds
That is all it takes to connect.
How to Connect Mailgun
The entire setup takes under a minute. Here is exactly what to do.
Find or Create Your Mailgun API Key
Log in to your Mailgun account. Click your profile icon in the top right corner and select API Securityfrom the dropdown menu. If you already have a key in the "Mailgun API keys" table, click the copy icon. Otherwise, click Create Key, give it a description (like "Valid Email Checker Integration"), and copy the key immediately.
You will need:
Private API Key
key-3ax6xnjp29jd6fds4gc373sgvjxteol0
Important: Mailgun only displays your full API key once when you create it. Copy it immediately and store it somewhere secure. If you lose it, you will need to create a new one. Make sure to use a Private API key — not a validation key or domain sending key.
Connect Your Account
In ValidEmailChecker, go to Integrations in the sidebar and find Mailgunin the available integrations. Click on the Mailgun card, enter a friendly connection name (like "Production Mailgun" or "Marketing Mailgun"), and paste the API key you copied. Click Connect Account and we will verify your key and sync your mailing lists.
Connection names matter:Using descriptive names like "Production Mailgun" or "Marketing Mailgun" helps when you have multiple accounts connected. You will thank yourself later.
Select a Mailing List and Configure
Once connected, go to Bulk Upload, click Connect Email Platform, select Mailgun, and click Sync Now. Your mailing lists will appear with subscriber counts. Select the list you want to verify, then choose your mode: Verify Only to review results before making changes, or Clean Automatically to remove invalid and disposable emails directly. Toggle on Remove Duplicates to save credits.
Delete is permanent:When you choose "Delete" for any email type, contacts are permanently removed from your Mailgun mailing list. This cannot be undone. If you are unsure, use "Unsubscribe" instead.
Track Results in Real Time
Click Import Listand you will be redirected to the Uploads & Results page where you can watch progress in real time. No need to refresh — the page updates automatically. When complete, click View Results to see the full breakdown. If you chose automatic cleaning, the changes are already applied to your Mailgun mailing list.
Want a visual walkthrough with screenshots?
Our help center has the full step-by-step guide with images for every screen.
Two Ways to Verify
Verify Only
Import and verify your mailing list without modifying anything in Mailgun. Review results, download reports, and decide what to do next — on your terms.
Best for:
Clean Automatically Recommended
Verify and clean in one step. Invalid emails are unsubscribed or deleted directly from your Mailgun mailing list — no manual work required.
You control each email type:
Unsubscribe vs Delete in Mailgun
Unsubscribe Preserves record
Marks the contact as unsubscribed in your Mailgun mailing list. They remain in the list but will not receive emails. The record is preserved for your reference.
Delete Permanent
Permanently removes the contact from your Mailgun mailing list. The record is gone and this action cannot be undone. Use for disposable and clearly invalid addresses.
Tracking Your Verification Progress
Once verification starts, you are automatically redirected to the Uploads & Results page where everything updates in real time — no refreshing needed.
What you will see for each task:
Task ID
Unique identifier for this verification
List Name
Your Mailgun list name with integration icon
Upload Date
When verification started
Total Emails
Number of members being verified
Status
Processing, Completed, Failed, or Deleted
Progress
Real-time percentage with progress bar
Processing
Verification in progress
Completed
Click "View Results" to see breakdown
With Warning
Some emails could not be processed (credits refunded)
Failed
Something went wrong (rare)
Managing Your Mailgun Connection
Connection Actions
Click the three-dot menu next to any connection on your Integrations page:
Sync Now
Refresh your mailing lists from Mailgun. Use after adding new lists or subscribers.
Rename
Change the connection display name to better identify the account.
Delete
Remove this connection. Does not affect your Mailgun account or mailing lists.
Multiple Accounts
Managing multiple Mailgun setups? Connect as many accounts as you need.
Click Connect Email Platform → Mailgun from Bulk Upload
You will see your existing connections listed
Click "+ Add Another Account"
Enter the new account's API key
Give it a unique, descriptive name
Suggested names: "Mailgun — Production," "Mailgun — Development," "Mailgun — Client ABC," "Mailgun — Marketing Team."
Credits & Billing
1 Credit = 1 Email
Same rate as all other verification methods.
Unknown = Refunded
Credits returned instantly for unverifiable emails.
Duplicates = Free
Toggle on Remove Duplicates to save credits.
Balance Visible
Check credits in the top-right corner of your dashboard.
Credits Running Low?
If you do not have enough credits for your list size, you can purchase more credits instantly or set up auto-refill so you never run out during a critical verification.
Team Member Access
Team members can connect their own Mailgun accounts and run verifications using the shared team credit balance. The account owner can see credits used by each team member in the transaction history.
Mailgun Tips
API Key Types
Mailgun has several types of API keys. Make sure you are using the right one for ValidEmailChecker to work properly.
US & EU Region Support
ValidEmailChecker works with both US and EU Mailgun regions. Just use your account's Private API key as normal — we handle the region routing automatically.
Transactional vs Marketing Email
Mailgun is primarily an email delivery service focused on transactional email — receipts, notifications, password resets, and similar automated messages. But many teams also use Mailgun for marketing email via mailing lists. ValidEmailChecker works with both use cases.
Transactional Lists
Verify to prevent hard bounces that damage your sender reputation and domain score.
Marketing Lists
Verify before campaigns to maximize deliverability and keep costs down.
Troubleshooting
"Invalid API Key" Error
Make sure you copied the entire key including any prefixes. Verify you are using a Private API key — not a validation key or domain sending key. Check that the key has not been deleted or regenerated in Mailgun. Go to Mailgun → Profile → API Security, create a new key if needed, and paste it fresh.
No Lists Showing Up
Check your Mailgun account for existing mailing lists — you need at least one list with subscribers. Make sure you are using a Private API key (not a validation key). Click Sync Now to refresh. If lists still do not appear, try creating a mailing list in Mailgun first, then reconnect.
Connection Shows "Error" Status
Your API key may have been regenerated or your account permissions changed in Mailgun. Delete the connection in ValidEmailChecker, generate a new API key in Mailgun (Profile → API Security), and reconnect with the fresh credentials.
Verification Stuck at 0%
Large lists may still be importing — wait a few minutes. Check the notification area in the top right for any messages. Try refreshing the page. If the verification remains stuck for over 30 minutes, contact our support team.
Changes Not Appearing in Mailgun
Wait for the verification to complete fully — changes only apply after completion. Refresh your Mailgun mailing list view. Check the verification results in ValidEmailChecker to confirm actions were taken. Make sure the action was not set to "Keep" by mistake.
Best Practices for Mailgun List Hygiene
Before Your First Verification
Ongoing List Hygiene
Recommended Actions
Frequently Asked Questions
Yes. Your API key is encrypted and stored securely on our servers. We use it only to connect to Mailgun on your behalf — to read your mailing lists and optionally update subscriber statuses. We never share your key or use it for any other purpose.
No. Email verification checks if addresses are valid without sending any emails. Your subscribers will not know verification happened. We never send emails through your Mailgun account.
Yes. You might want to re-verify if significant time has passed, you have added new subscribers, or you want to catch newly invalid addresses. Email data decays at roughly 2% per month, so periodic re-verification keeps your lists healthy.
Mailgun is primarily an email delivery service focused on transactional email (receipts, notifications, password resets), while platforms like Mailchimp or ConvertKit focus on marketing automation. ValidEmailChecker works with both types — keeping your mailing lists clean regardless of how you use them.
When you choose "Unsubscribe" for an email type, ValidEmailChecker marks those contacts as unsubscribed in your Mailgun mailing list. They remain in the list but will not receive emails. This preserves the record while preventing bounces.
Absolutely. Deleting a connection just removes it from ValidEmailChecker — your Mailgun account and mailing lists are completely unaffected. Reconnect anytime with the same or a new API key. Your verification history is preserved.
Yes. ValidEmailChecker works with both US and EU Mailgun regions. Just use your account's API key as normal — we handle the region routing automatically.
If we cannot determine whether an email is valid or invalid — for example, if the mail server did not respond or timed out — the result is marked as "Unknown" and the credit is automatically returned to your account. You only pay for definitive results.
Ready to Clean Your Mailgun Lists?
Sign up, connect your Mailgun account, and verify your first mailing list in under two minutes. 200 free credits included — no credit card required.
Get Started Free200 free credits · No credit card · Results in minutes