MailStream

Verify every address before you spend a stamp.

CASS-certified, USPS-standardized address verification, available as a standalone API or automatically applied to every mail piece you send through Mailstream.

Quick start

One call. Verified in milliseconds.

Send a raw address and get back a standardized, deliverability-scored result. Works for single lookups or batches of millions.

Capabilities

More than a yes/no check.

Real-time verification
Validate addresses at the point of entry: checkout forms, CRM records, lead capture. Sub-200ms response times keep user flows fast.
Batch processing
Upload a CSV or send thousands of addresses via API. MailStream verifies, standardizes, and flags undeliverable entries in bulk.
Autocomplete
Suggest verified addresses as users type. Reduces form abandonment and ensures clean data from the first keystroke.
USPS standardization
Addresses are reformatted to USPS Publication 28 standards: proper abbreviations, ZIP+4 appended, suite lines normalized.
Deliverability scoring
Each address receives a confidence score from 0 to 100. Use it to gate mail sends, flag risky records, or prioritize list cleaning.
Vacancy & type detection
Know whether an address is residential or commercial, and whether it is currently vacant. Avoid mailing to empty buildings.

Verification pipeline

Five stages. Sub-200ms.

Every address passes through a multi-stage pipeline that parses, verifies, standardizes, and scores before returning a result. The entire flow completes in under 200 milliseconds.

  1. Input

    Raw address received

  2. Parse

    Components extracted

  3. Verify

    CASS certification

  4. Standardize

    USPS Pub 28 format

  5. Score

    Deliverability 0-100

200ms
Average verification time
98%
CASS accuracy rate
10x
ROI on verification spend
5%
Average undeliverable rate
We are the manufacturer
No middlemen or delays. Your mail goes directly from our floor to USPS, with quality checks.
HITRUST-certified facility
Your data runs in a HITRUST-certified environment with enterprise security and compliance.
25+ years of expertise
Twenty-five years in direct mail, starting with an early online printer in 1998. We have tackled every edge case.
Real-time USPS tracking
Track Intelligent Mail barcodes. Know when printed, in transit, and delivered via dashboard, API, or webhooks.

Real results

Teams trust Mailstream to deliver.

We replaced three vendors with Mailstream and finally got full visibility from print to delivery. Tracking every piece in real time changed how we measure direct mail.

Daniel H.

VP of Growth, Northbridge Labs

The HTML design tool is a game changer. We design, personalize, and send without ever leaving the platform. No more emailing PDF proofs back and forth.

Olivia W.

VP of Growth, Northbridge Labs

We integrated the API in a day and had automated compliance notices running by the end of the week. The HITRUST certification made our security team very happy.

Ethan K.

VP of Growth, Northbridge Labs

Join agencies, SaaS teams, and operators using MailStream to automate direct mail at scale without manual vendors or guesswork.