Email lists get dirty for ordinary reasons.
Someone mistypes an address on a signup form. An old mailbox disappears. A visitor uses a disposable address. An imported list contains contacts that have not been mailed in years. The bigger the list and the more ways contacts can enter it, the more of these addresses accumulate.
The problem is not only the wasted send. Mailing addresses that do not exist will increase bounce rates and work against the sender reputation you depend on to reach valid subscribers.
The usual fix is: export a list from Interspire Email Marketer, upload it to a verification service, wait for the results, clean the file and import it back into IEM. Then repeat the process later because new contacts have entered the system since the last cleanup, as well as the natural attrition of valid email addresses.
We built the Email Verification Addon for Interspire Email Marketer to simplify that workflow.
It does two jobs:
- Verify contacts as they enter Interspire.
- Bulk-verify the contacts already in on your lists.
Everything is managed from inside Interspire Email Marketer.
Disclosure: ClearBounce links on this site may be affiliate links. If you sign up through one of those links, we may earn a commission at no additional cost to you.
Stop exporting and re-importing lists
This is the main reason the addon exists.
A third-party verification service can tell you whether an address looks deliverable. The missing piece for an IEM user is what happens before and after that check.
With the addon installed, verification becomes part of the IEM contact workflow itself.
New contacts can be checked when they arrive through a public form, a manual add, the XML API or an import. Existing contacts can be verified in bulk without creating a separate CSV cleanup process.
The result stays attached to the contact in IEM, where you can log it, segment on it and decide what IEM should do next.
Stop bad addresses at the door
For contacts entering IEM, the addon can evaluate addresses for:
- Invalid mailboxes
- Disposable addresses
- Role-based addresses
- Catch-all domains
- Risky results
- Unknown results
The underlying ClearBounce verification also performs syntax, MX, and SMTP mailbox checks.
You decide the policy for each verdict.
For example, you might block invalid and disposable, flag risky and catch-all, and allow the rest. Another installation may want a more permissive policy. The addon does not force one definition of a “good” subscriber onto every IEM user.
Live or Deferred: choose where the waiting happens
Mailbox verification involves an external service and, in many cases, a remote mail server. That means a live check can take longer than a simple form submission.
For an administrator manually entering one address, waiting for an immediate answer may be perfectly reasonable. For a visitor submitting a public signup form, it usually is not. That is why the addon supports Live and Deferred verification by entry point.
Live verification
Live mode checks the address before it is accepted.
Use it when you want IEM to make the allow flag or block decision immediately and the person submitting the address can wait for the response.
Deferred verification
Deferred mode accepts the subscriber immediately (independently of other Interspire checks) and sends the verification job through the IEM scheduler.
The subscriber receives a Pending verification status until the result comes back. If the result matches a verdict your policy blocks, the addon can unsubscribe, delete or flag the contact according to your configuration.
This lets public forms stay responsive without giving up verification.
Verification should not cost you a subscriber
The addon is designed to fail open. If the verification provider is temporarily unavailable, a request times out, or the provider account cannot complete the check, IEM accepts the subscriber as unverified instead of rejecting the signup because an external service had a problem.
Verification is there to protect list quality. It should not turn a possible outage into lost subscribers.
Clean the list you already have
Preventing new bad addresses is one side of the problem. Installations will likely already have contacts that need attention.
Bulk verification lets you select existing lists and start a background verification job from IEM.
The addon batches addresses through the provider’s API while IEM’s scheduler handles the work in the background. You do not need to keep a browser window open while a large list is processed.
When the job finishes, you can:
- Review the count for each verdict
- Export invalid addresses to CSV
- Unsubscribe invalid contacts in one action
- Use verification status when building IEM segments
The workflow remains inside the application where the contacts already live.
Reuse verification results
The addon keeps a cache of verification verdicts.
The cache has a configurable time-to-live, with a default of 60 days. While a result is still valid, IEM can reuse it if the same address appears again on another list, in another import or in a later verification job.
Bulk jobs check that cache before sending an address to the provider.
This matters most on IEM installations where contacts overlap across several lists. Once a cached result expires, it will need a fresh check. The point is to avoid repeat verification calls when a recent result is already available.
See what happened after the check
Verification is not very useful if the result disappears after the API response. The addon keeps a filterable Verification Log covering:
- Individual Subscribers
- Bulk jobs
- Rejected signups that did not become IEM contacts
That last category is important because a blocked signup would otherwise leave very little trace inside IEM.
For contacts that do exist, the addon also records a verification event on the contact timeline and maintains an Email verification status custom field.
Because that status is searchable and segmentable, verification becomes part of the normal IEM audience workflow. You can build segments around it rather than exporting another file every time you want to exclude a class of addresses.
Also built for reseller and multi-user IEM installations
A single-user installation mainly needs verification and list cleanup. A hosted IEM platform has another problem: who is allowed to use verification, and how much can each customer consume?
The addon includes per-user and per-group controls designed for that model:
- Monthly and lifetime allowances by user group
- Per-user usage metering
- Usage audit ledger
- Configurable usage-warning emails
- Manual grants for individual users
- Separate view, verify, bulk and manage permissions
An email marketing service provider using Interspire can map verification allowances to existing subscription tiers instead of having to give every tenant unrestricted access to a shared provider account.
The provider API key remains centrally managed and is restricted to system administrators.
ClearBounce provides the verification
The verification engine behind the addon is ClearBounce.
The IEM addon handles the workflow, policies, caching, background jobs, logging, segmentation and multi-user controls. ClearBounce performs the address verification.
That distinction is important before make the purchase:
- The IEM addon costs $149 one-time and includes 12 months of addon updates.
- ClearBounce API usage and verification credits are separate.
- ClearBounce Shield is a separate ClearBounce product and is not included with the addon.
ClearBounce provides test API keys. You can use a test key to configure your policies and exercise the integration without consuming live verification credits.
For development and staging environments, the addon includes a deterministic offline stub provider.
Want to validate the form before it reaches IEM?
There is another option for public-facing forms.
ClearBounce also offers ClearBounce Shield, a separate form-validation product that runs in the browser.
Shield is not part of the IEM Email Verification addon. It is complementary.
You add a lightweight JavaScript snippet to a website form, configure the types of addresses you want to reject, and Shield validates the email address in real time as the visitor types. It can block the same set of type of addresses such as disposable addresses, catch-all addresses, free email providers or addresses that match your own rules before the form is submitted.
That gives you two different layers of protection:
ClearBounce Shield protects the form. The IEM addon protects the contact system behind it.
Shield is useful when you specifically want immediate feedback on a public form before the submission reaches Interspire Email Marketer.
The Email Verification addon works at the application level. It can verify contacts arriving from forms, and also covers manual additions, XML API requests and imports, and it can bulk-verify contacts already stored in IEM. It also keeps the verification result inside IEM for logging, segmentation and multi-user usage control.
You do not need Shield to use the addon, and you do not need the addon to use Shield. For installations where public form quality is especially important, using both gives you form-level protection at the front end and broader verification and list hygiene inside IEM.
ClearBounce currently lets you start Shield with 100 free checks with your Email Verification account.
Which IEM version do you need?
For the complete feature set, use Interspire Email Marketer 8.8.0 or later.
IEM 8.8.0 includes the subscriber-ingress event used for automatic verification when contacts enter the system.
If you are running IEM 8.7.5, the bulk-verification functionality still works, but automatic signup and subscriber-ingress verification does not.
The addon also requires:
- PHP 8.3 or later
- PHP cURL extension
- IEM’s cron/scheduler enabled
- A ClearBounce API key
The goal is simple: make list hygiene part of IEM
Email verification is not new. The workflow was the hurdle.
You should not have to export your audience to another application to find out which addresses are still valid.
Email Verification for Interspire Email Marketer keeps the verification step inside IEM, applies your policy as contacts arrive, cleans existing lists in the background and keeps the result available for segmentation and auditing afterward.
And if you want to stop unwanted addresses even earlier, ClearBounce Shield can sit separately on your public-facing forms and validate the address before the submission ever reaches IEM.
The addon is available for $149 one-time, including 12 months of updates. ClearBounce verification credits are purchased separately.
Get Email Verification for Interspire Email Marketer
For installation, Live vs Deferred modes, policies, bulk jobs, and credits, see the Email Verification Addon documentation.