docs(smtp): document Params.FromHeader usage pattern

[Copilot]

smtp.Params.FromHeader was undocumented in docs/smtp.md, leaving callers without guidance on which field to use as the From: message header vs. the SMTP envelope sender.

Changes

• docs/smtp.md: Adds a Params fields section clarifying the From/FromHeader split — From is the bare address used internally by smtp.Send for the SMTP envelope; FromHeader is the RFC 5322-formatted string (properly quoted/MIME-encoded via mail.Address.String() when a display name is present) to set as the From: header in composed messages.

params, err := cfg.Validate()

msg := "From: " + params.FromHeader + "\r\n" +
    "To: recipient@example.com\r\n" +
    "Subject: Hello\r\n" +
    "\r\n" +
    "Message body.\r\n"

err = smtp.Send(ctx, params, "recipient@example.com", []byte(msg))

Greptile Summary

This docs-only PR adds a ## Params fields section to docs/smtp.md explaining the distinction between Params.From (bare SMTP envelope address) and Params.FromHeader (RFC 5322-formatted string for the From: header). The description and code example accurately reflect the implementation in smtp.Validate(), including the mail.Address.String() quoting/MIME-encoding behaviour and the fallback to the bare address when no display name is present.

Confidence Score: 5/5

Safe to merge — documentation-only change with no code modifications.

The PR adds only documentation. The new section accurately reflects the implementation in smtp.go (the From/FromHeader split, mail.Address.String() behaviour, and bare-address fallback are all correct). The previous thread concern about unchecked smtp.Send error has been addressed. No logic, security, or correctness issues found.

No files require special attention.

Important Files Changed

Filename	Overview
docs/smtp.md	Adds a Params fields section documenting the From/FromHeader split with a table and code example; content accurately reflects the implementation in smtp.go.

Sequence Diagram

sequenceDiagram
    participant App
    participant cfg as smtp.Config
    participant params as smtp.Params
    participant server as SMTP Server

    App->>cfg: LoadConfig()
    App->>cfg: Validate()
    cfg->>params: From = parsed.Address
    cfg->>params: FromHeader = parsed.Address (no display name) OR mail.Address.String() (with display name)
    cfg-->>App: Params

    App->>App: Build message using params.FromHeader as From: header
    App->>server: smtp.Send(ctx, params, to, msg) uses params.From for MAIL FROM envelope

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_{Reviews (2): Last reviewed commit: "docs(smtp): fix RFC references and add e..." | Re-trigger Greptile}

[Copilot]

Pull request overview

Documents how to correctly use smtp.Params.From vs smtp.Params.FromHeader so callers can distinguish the SMTP envelope sender (MAIL FROM) from the RFC 5322 From: header value when composing raw messages.

Changes:

• Adds a Params fields section explaining the From/FromHeader split and when they differ.
• Adds a short example showing params.FromHeader used in the From: header before calling smtp.Send.

Show a summary per file

File	Description
docs/smtp.md	Documents Params.FromHeader usage and provides an example for composing From: correctly.

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• Files reviewed: 1/1 changed files
• Comments generated: 1