Sincerely

Sincerely turns CRM or CSV audiences into personalized postcards and letters for B2B campaigns. It is best suited to revenue teams that need account-level targeting, source-backed copy and measurable holdouts rather than a basic mail-merge service. The central question is whether its approval controls and attribution justify a paid, capped-volume program.

Overview

Sincerely connects campaign audiences to Salesforce, HubSpot or CSV data, then creates one-to-one printed mail with measurement built in. Its focus on account-level holdouts makes it a strong fit for teams evaluating lift across target accounts. Teams wanting handwritten notes, gifts or broad consumer-mail formats should look elsewhere because only postcards and letters are live.

Key features

Salesforce and HubSpot synchronization brings in account, contact, opportunity-stage and campaign-membership data. CSV import covers teams outside those systems, but it puts audience preparation on them. The supported formats are 4x6 and 6x9 postcards and letters.

Personalized drafts use account research and attach each factual claim to a source. Human approval is mandatory before printing, and edits are versioned. That combination makes generated copy auditable and preserves an editorial checkpoint, although it adds a required step to every campaign.

Address verification and correction are included on every plan. Low-confidence addresses are routed for review, reducing avoidable delivery problems without making the process fully automatic. Account-level holdouts are also universal, and five of eight campaign types measure lift against a holdout; Growth is the point at which all eight types become available.

Lob prints US postcards and letters, while a Canadian provider handles Canadian pieces. Customers do not contract with either provider through Sincerely. When a plan reaches its monthly cap, live campaigns pause instead of sending extra pieces, so forecasting volume is essential.

Data is encrypted in transit, workspace access is scoped, and state-changing actions are recorded in an audit log. Sincerely says it neither sells personal information nor uses 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. There is no API access.

Pricing

The Audit plan is useful for checking data, deliverability and creative, but it cannot send mail. Pilot is a contained 100-piece proof of concept and its one-time fee can reduce the first continuing month. Core is the entry point for regular mailing and CRM sync; Starter suits a larger program but still offers only standard reports. Growth is for teams that need the complete campaign-measurement set, attribution and spending controls. Scale is aimed at high-volume organizations requiring governance and a reporting contact. There is no free trial, and paid plans start at $250 per month.

Platforms

Sincerely is web-based. Salesforce and HubSpot are the native CRM connections, CSV import is supported, and there is no API. MCP access works through browser sign-in and OAuth, with printing and spending actions withheld from agents.

Who it's for

Choose Sincerely if your B2B team already works from account and opportunity data, wants source-backed personalization, and needs holdout-based measurement with human sign-off. It is a poor match for handwritten or gift campaigns, unrestricted volume, API-first automation, or a no-cost sending workflow.

Pros and cons

• Pros: Account-level holdouts are included on every plan, so measurement is not limited to the highest tier.
• Pros: Source-pinned drafts, versioned edits and mandatory approval make generated copy reviewable before printing.
• Pros: Address correction and low-confidence review are included across plans.
• Cons: The free Audit plan cannot mail, while live programs begin at $250 per month.
• Cons: Monthly caps pause campaigns when reached, making capacity planning important.
• Cons: Handwritten notes, gifts and API access are unavailable.

Alternatives

Direct Mail Automation Software is the broader category starting point when you want to compare this approach with other mailing tools.

Pick ZAP~POST instead when API and web access, webhooks and logs, and up to 60,000 Zaps per year on its free annual Pro plan matter more than Sincerely's holdout workflow.

DocuPost is a better fit for pay-per-mailpiece sending, including a free plan with no send limit, when one user and DocuPost branding are acceptable.

Choose Inkit when signature requests and document storage are the priority.

Postalytics suits teams seeking unlimited campaigns, templates and lists on a free plan with per-piece mail charges.

Stannp is an option for a free, high-contact-capacity setup and flexible send volume.

thanks.io fits pay-as-you-go users who require full API access.

Lob Address Verification is the focused choice when address verification, rather than campaign orchestration, is the main need.

PostPilot is worth considering for a free start with platform access and analytics, paying for postcards and postage.

Verdict

Sincerely is the right choice for B2B teams that want CRM-grounded, individually written direct mail with approval controls and holdout measurement at the center. Its main reason to choose it is the combination of source-backed personalization and account-level experimentation. Look elsewhere if you need an API, gifts or handwritten mail, unlimited volume, or a free plan that can actually send.