Sincerely

Sincerely is B2B direct-mail software that uses CRM or CSV audiences to create personalized printed pieces and measure campaigns with account-level holdouts. Salesforce and HubSpot connections sync account, contact, opportunity-stage, and campaign-membership information, and CSV import is also available. The product generates personalized draft copy from account research and attaches a source to each factual claim. A person must approve drafts before printing, and edits are versioned. Postcards and letters can be mailed; handwritten notes and gifts are not currently live because fulfillment adapters have not been built. Address verification and correction are included on every plan, with uncertain addresses sent for review. The company says five of eight campaign types measure lift against a holdout. The free Audit plan supports imports, mailability checks, brand materials, and draft editing, but cannot mail. Paid plans start at $250 a month, while the Pilot costs $199 once. Live campaigns pause when a plan reaches its monthly cap. Data is encrypted in transit, workspace access is scoped, and state-changing actions are logged.

Sincerely combines audience imports, personalized mail drafts, address checks, and holdout measurement for direct-mail campaigns. Its free plan is limited to preparation, and live campaign capacity is capped by plan.

It suits B2B teams sending personalized postcards or letters to CRM or CSV audiences and measuring campaign outcomes with holdout groups. Teams needing handwritten notes or gifts should note those formats are not live.

Sincerely is a B2B direct-mail platform that turns CRM or CSV audiences into individualized postcards and letters, with controls for copy review, address quality, and campaign measurement. It is best suited to account-based marketing teams already working in Salesforce or HubSpot and willing to manage a human approval step. Teams needing handwritten outreach, gifts, an API, or inexpensive high-volume sending should look elsewhere.

Overview

Sincerely connects audience data, personalized print, and holdout-based measurement in one web application. Salesforce and HubSpot can supply account, contact, opportunity-stage, and campaign-membership data; CSV import covers teams outside those systems. The result is a workflow aimed at targeted B2B programs rather than broad consumer mail blasts.

Live fulfillment currently covers 4x6 and 6x9 postcards and letters. Handwritten notes and gifts are not available to mail, which narrows its usefulness for appreciation or gifting programs. Lob prints US pieces and a Canadian provider prints Canadian pieces; Sincerely remains the customer relationship rather than having customers contract directly with either vendor.

Key features

The writing system creates one-to-one drafts from account research and attaches each factual claim to a source. Human approval is mandatory before anything prints, and the platform versions edits. That combination makes generated copy auditable and gives marketing or sales reviewers control, but approval is a required operational step rather than a bypassable option.

Address verification and correction are included on every plan. Low-confidence addresses are routed to review instead of being treated as reliable automatically, a practical safeguard for teams paying to put physical mail in front of named accounts.

Account-level holdouts are also included across plans, and five of eight campaign types measure lift against a holdout. This makes experimental measurement part of the product's baseline rather than a separate analytics purchase. Growth is the plan that exposes all eight campaign types, so lower tiers have a narrower measurement menu.

Security controls include encryption in transit, workspace-scoped access, and audit logs for state-changing actions. Sincerely says it does not sell personal information or use CRM data to train models or benefit another customer. MCP clients can connect through browser sign-in and OAuth, but agents cannot perform actions that print or spend money. There is no API access.

Monthly caps are operational, not merely billing thresholds: when a plan reaches its cap, live campaigns pause instead of printing additional pieces. That prevents surprise overages but can interrupt a time-sensitive sequence.

Pricing

The Audit plan is free ($0.00 per free) and includes CRM or CSV import, a mailability audit, brand kits and designs, and draft generation and editing. It cannot mail, so it is useful for preparation and evaluation, not a live campaign.

Pilot costs $199.00 once, billed one time, and includes 100 pieces, an account-level holdout, and no per-piece charges. The payment is credited toward the first month if you continue, making it a contained way to run an initial program without committing to a recurring tier.

Core is $250.00 per month, billed $250 /mo. It includes 150 pieces, permits up to 600 a month, supports letters and postcards, adds Salesforce and HubSpot sync, and includes account-level holdouts. This is the entry point for ongoing CRM-connected sending, but its ceiling is modest.

Starter is $500.00 per month, billed $500 /mo, with 350 pieces included, a limit of 2,000 a month, and standard reports. Growth is $1,500.00 per month, billed $1,500 /mo, with 1,300 pieces included and up to 10,000 a month, plus all eight campaign types, approval workflows, spend limits, and opportunity attribution. Scale is $3,500.00 per month, billed $3,500 /mo; it includes 3,700 pieces, supports up to 25,000 a month, and adds governance and roles, a named report contact, and the lowest per-piece prices. Paid plans therefore suit progressively larger programs, while every tier remains constrained by a hard live-volume cap.

Platforms

Sincerely runs on the web. Salesforce and HubSpot are the supported CRM connections, CSV is supported for imports, and there is no API access. MCP support is limited to browser sign-in and OAuth, with printing and spending actions unavailable to agents.

Who it's for

Choose Sincerely if your B2B team targets named accounts, wants CRM context carried into personalized print, and needs holdout measurement with address-quality checks. Core fits smaller recurring programs; Starter and Growth fit teams scaling volume or reporting depth; Scale is for organizations that need governance, roles, and the largest stated capacity. Audit and Pilot suit preparation or a first paid run.

It is a poor fit for handwritten-note or gift campaigns, API-first operations, or programs that cannot tolerate a pause when a monthly cap is reached.

Pros and cons

• Pro: Source-pinned personalized drafts and versioned human edits make generated claims reviewable before printing.
• Pro: Address correction and low-confidence review are included on every plan, reducing avoidable delivery errors.
• Pro: Account-level holdouts are standard, with opportunity attribution and all eight campaign types available on Growth.
• Con: The free Audit plan cannot mail, and live programs start at $250.00 per month after the one-time Pilot option.
• Con: Handwritten notes, gifts, and API access are absent, limiting channel and integration flexibility.
• Con: Campaigns pause at the monthly cap rather than continuing with extra pieces.

Alternatives

Handwrytten is the better choice when handwritten cards are the central format; it offers Android, iOS, web, and API access, with Silver at $100.00 per month for 24 cards.

PostBridge is worth considering when you need a lower-cost paid service with a free trial and Android, iOS, web, and API platforms.

DocuPost fits teams wanting a free web/API tier for letters and postcards with no send limit and pay-per-mailpiece billing.

Stannp is an alternative for a freemium web/API mailing service with a free contact allowance and virtual-printer items.

thanks.io suits buyers seeking pay-as-you-go pricing, a free plan, and full API access.

ZAP~POST is an option for automation-led campaigns using integrations, webhooks, and logs.

Inkit is a better match for teams focused on document signature requests and storage rather than direct-mail measurement.

Lob Address Verification is the narrower choice when address validation is the primary requirement.

See the broader Direct Mail Automation Software category for more options.

Verdict

Sincerely is a strong choice for CRM-driven B2B teams that want personalized postcards and letters, accountable copy review, verified addresses, and holdout measurement in one workflow. Its main reason to choose it is the combination of account-level targeting and built-in experimentation; its main reason to look elsewhere is the recurring cost and hard capacity limits, compounded by no API and no handwritten or gift fulfillment.