email-signing

A command for adding a GPG/PGP digital signature to outgoing emails. The signature helps recipients verify who sent the message and whether it was changed, but it does not hide the email contents.

In plain words
What is it for?
Installing or using GPG keys, selecting a signing key, and signing emails sent through the Nylas CLI.
Why use it?
It lets recipients check an email's identity and integrity instead of relying only on the visible sender address.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/nylas/cli/email-signing
Clone the repo
git clone --depth 1 https://github.com/nylas/cli
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,456 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00000 $0.02456
Opus 5 $0.00000 $0.01228
Sonnet 5 $0.00000 $0.00491
Haiku 4.5 $0.00000 $0.00246

Measured 2d ago against content hash 68d1c5f2cd1d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

email-signing scanned grade B with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

sudo apt install gnupg
docs/commands/email-signing.md · 403 lines

How it starts

The opening of the file, as written. The whole thing — 403 lines — stays where its author put it; the contents beside it link to each section on GitHub.

GPG Email Signing

Sign outgoing emails with your GPG/PGP key for cryptographic authentication.


Overview

The Nylas CLI supports signing emails with GPG (GNU Privacy Guard) using the OpenPGP standard (RFC 3156). Signed emails allow recipients to verify:

  • The email was sent by you (authentication)
  • The email content hasn't been tampered with (integrity)

Note: This feature signs emails but does not encrypt them. Email content remains readable.


Prerequisites

1. Install GPG

Linux (Debian/Ubuntu):

sudo apt install gnupg

macOS:

brew install gnupg

Windows: Download from: https://gnupg.org/download/

2. Generate a GPG Key

If you don't have a GPG key:

gpg --gen-key

Follow the prompts to create your key. Use the same email address you send emails from.

3. Configure Git (Optional but Recommended)

Set your default signing key:

gpg --list-secret-keys --keyid-format=long
# Copy your key ID (e.g., 601FEE9B1D60185F)

git config --global user.signingkey 601FEE9B1D60185F

4. Configure Nylas CLI (Optional)

Set default GPG key and auto-sign preferences:

# Set default GPG signing key
nylas config set gpg.default_key 601FEE9B1D60185F

# Enable auto-sign for all outgoing emails
nylas config set gpg.auto_sign true

# View GPG configuration
nylas config get gpg.default_key
nylas config get gpg.auto_sign

Key Selection Priority:

  1. --gpg-key <key-id> flag (highest priority)
  2. gpg.default_key from Nylas config
  3. From email address (auto-detected)
  4. user.signingkey from git config (lowest priority)

Usage

List Available GPG Keys

See all GPG keys available for signing:

nylas email send --list-gpg-keys

Output:

Available GPG signing keys (1):

1. Key ID: 601FEE9B1D60185F
   Fingerprint: E4D944EDAD2E329591A8854B07DD577603B27996
   UID: John Doe <[email protected]>
   Expires: 2031-01-31

Default signing keys:
  From Nylas config: 601FEE9B1D60185F
  From git config: 601FEE9B1D60185F

Read the full file on GitHub · 403 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 403 lines · 0 tokens per session scan B 68d1c5f2cd1d

Subscribe to this mod's changes

email-signing is a command published in the GitHub repository nylas/cli (68 stars, last pushed 14d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 2,456 tokens. A static security scan graded it B with 1 finding (asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.