Solmail MCP Server

Send physical mail with Solana cryptocurrency - AI agents can send real letters worldwide. The solmail mcp server wraps that behind the Model Context Protocol, so an assistant can use it through 4 defined tools rather than through you.

What it actually does

Claude: [calls get_mail_quote] Cost: $1.50 (~0.015 SOL) for domestic US mail [calls send_mail] Letter sent! Letter ID: ltr_abc123 Tracking: 9400000000000000000000 Payment: 0.015 SOL (tx: 5j7s...) Delivery: 3-5 business days ```

• Physical Mail — -- Letters printed and mailed to 200+ countries via Lob.com
• Solana Payments — -- Pay with SOL on devnet (testing) or mainnet (production)
• Non-Custodial — -- Direct wallet control, no intermediaries
• AI-Native — -- Built specifically for MCP agent integration
• Demo Mode — -- Test with devnet SOL and Lob test API at zero cost

Adding it to your client

The server ships on npm as solmail-mcp, so your MCP client can launch it on demand — there is no separate build step. Add the server block to your client's configuration, restart it, and the tools register themselves.

Its toolset

Everything the assistant can do here goes through one of these:

• get_mail_quote — Get price quote for sending mail (country, color options)
• send_mail — Send a physical letter with Solana payment
• get_wallet_balance — Check agent wallet SOL balance
• get_wallet_address — Get wallet address for funding

Configuration

You will need 3 environment variables: SOLANA_NETWORK, SOLANA_PRIVATE_KEY, SOLMAIL_API_URL. The server will not start without them, which is usually why the tools fail to appear on a first run. Keep credentials in your client's env block or a secrets manager rather than in a file you might commit.

Caveats

• It runs with your machine's permissions. That is convenient and also the reason to think about what you point it at before you approve a tool call.
• Missing credentials fail quietly in some clients — if no tools show up, check the environment block first.
• MCP clients confirm each tool call by default. Leave that on until you have watched what the solmail mcp server does with a few real requests.

When to reach for it

Among the developer tooling options, the useful question is rarely "what can it do" but "what does it cost you to run" — permissions, credentials, and how much of your context its toolset consumes. Solmail's toolset — get_mail_quote, send_mail, get_wallet_balance and 1 more — is a fair guide to whether it matches your workflow. It is maintained by ExpertVagabond; worth a glance at recent repository activity before you build anything load-bearing on it.

This entry was verified against Solmail's own documentation before publication; SyncDev keeps the directory reviewed rather than auto-generated.