Email

rlwatch sends alerts over SMTP using the standard library smtplib. Works with Gmail (with an app password), AWS SES, SendGrid, Mailgun, or any other SMTP relay.

Setup

alerts:
  email:
    smtp_host: smtp.gmail.com
    smtp_port: 587
    smtp_user: alerts@yourcompany.com
    smtp_password: "..."          # use an app password for Gmail
    from_addr: alerts@yourcompany.com
    to_addrs:
      - oncall@yourcompany.com
      - you@yourcompany.com

Or via environment variables:

export RLWATCH_SMTP_HOST=smtp.gmail.com
export RLWATCH_SMTP_PORT=587
export RLWATCH_SMTP_USER=alerts@yourcompany.com
export RLWATCH_SMTP_PASSWORD="..."
export RLWATCH_EMAIL_FROM=alerts@yourcompany.com
export RLWATCH_EMAIL_TO="oncall@yourcompany.com,you@yourcompany.com"

RLWATCH_EMAIL_TO is comma-separated and auto-enables the email channel when set.

Message format

Each alert is sent as a multipart message with both plain-text and HTML parts:

• Subject: [rlwatch CRITICAL] entropy_collapse — Run grpo_v3_exp12 Step 320
• Plain text: the alert message, the recommended action, and a key/value list of metric values
• HTML: the same content with severity-coded headers (red for critical, orange for warning) and a metric table

Most modern email clients show the HTML part. Plain-text is the fallback for terminal mail clients.

TLS

The sender always calls STARTTLS after connecting. Plain unencrypted SMTP is not supported — for SMTP relays that don't require auth, leave smtp_user and smtp_password empty and TLS still happens.

Failure handling

SMTP errors are logged at error level. The send runs in a daemon thread, so SMTP timeouts or auth failures don't block the training loop. If your SMTP relay is down for hours, you'll see error log lines but training keeps running.

Gmail-specific notes

Gmail requires an app password — your regular Google account password won't work over SMTP. Generate one under Google Account → Security → 2-Step Verification → App passwords.