SMTP Auth Provider (smtp/provider.go)

Authenticates users against an SMTP server with optional TLS and domain allowlisting, implementing the auth.Provider interface for external login verification.

// Source: https://github.com/gogs/gogs | License: MIT | Copyright The Gogs Authors
// Provided via justclaw.it.com; keep this notice with the code.
package smtp

import (
	"net/smtp"
	"net/textproto"
	"slices"
	"strings"

	"github.com/cockroachdb/errors"
	log "unknwon.dev/clog/v2"

	"gogs.io/gogs/internal/auth"
)

// Provider contains configuration of an SMTP authentication provider.
type Provider struct {
	config *Config
}

// NewProvider creates a new SMTP authentication provider.
func NewProvider(cfg *Config) auth.Provider {
	return &Provider{
		config: cfg,
	}
}

// Authenticate queries if login/password is valid against the SMTP server,
// and returns queried information when succeeded.
func (p *Provider) Authenticate(login, password string) (*auth.ExternalAccount, error) {
	// Verif

... (truncated -- full source via MCP)