Passwordless authentication delivery

One sender.
Forget passwords.

Deliver one-time codes and magic links through one trusted email layer—fast for real users, rate-limited against attackers, and built on infrastructure you control.

Request early access See how it works
  • OTP + magic links
  • Single-use codes
  • Identity + IP throttling

01 / Platform

The secure delivery layer between sign-in and the inbox.

Help clients remove passwords without creating a new abuse channel. Every authentication request is attributable, throttled and short-lived.

SMTP + API

OTP and magic links, one integration

Give every client or application its own credential, limits and audit trail while delivering through a consistent sender identity.

SPF authorizedDKIM signedDMARC aligned

Authentication as a prerequisite

Use a coherent sender, signing domain and SMTP identity, with TLS and valid reverse DNS supporting the delivery path.

Controlled network

Abuse resistance by default

SenderMesh accepts authentication traffic from reviewed clients and slows enumeration, resend floods and bot-driven inbox bombing.

  • Generic responses prevent account discovery
  • Expired codes are never sent
  • Permanent failures are suppressed

02 / Security + reputation guardrails

Fast for users. Expensive for attackers.

Tenant volume, source traffic and end-user attempts are limited separately, before delivery work is accepted.

Evaluation

New client
100

auth emails / day

  • Reviewed integration
  • Identity and device limits
  • Authentication traffic only
Verified default

Verified

Trusted client
1,000

auth emails / day

  • Quota check before enqueue
  • Privacy-reduced audit trail
  • Domain-wide Gmail tracking

Established

Reviewed traffic
Custom

evidence-based volume

  • Measured warm-up
  • Complaint-rate review
  • Controlled growth

DELIVERY RULE: an expired OTP must never leave the queue. Time-based validity always wins over retry attempts.

Resend interval60 secper identity
Attempt ceiling5 / hourper identity
Daily ceiling10 / dayper identity
Source ceiling≈20 / hourper IP or device

Return the same public response whether an account exists. For sensitive accounts or transactions, offer passkeys, security keys or another independent factor.

03 / Deliverability

Wanted sign-in mail reaches more inboxes.

Aligned authentication, predictable user-triggered volume, clean recipients, suppression and strict tenant review protect the domain and IP from looking like spam.

04 / Field guide

A four-second queue can send 21,600 messages a day.

Rate calculations are easy to underestimate. The SenderMesh guide turns Gmail classification, domain-wide tracking, quotas and retry behavior into concrete engineering decisions.

Read the Gmail bulk sender guide

Private beta

Replace passwords.
Keep the trust.

Start with a small group of verified applications. Make sign-in easier for people and harder to automate at scale.

Request early access