Method signMessage

internal/outbound/sender.go:315–333

signMessage looks up a DKIM keypair for the given domain and returns a signed copy of the message. Returns (nil, false) when no key is stored for the domain or when signing fails — callers proceed with the unsigned message rather than failing the send.

(message []byte, domain string)

// stored for the domain or when signing fails — callers proceed with
// the unsigned message rather than failing the send.
func (s *Sender) signMessage(message []byte, domain string) ([]byte, bool) {
	if s.dkimLookup == nil || domain == "" {
		return nil, false
	}
	selector, privKey, err := s.dkimLookup.GetDKIMKeyInternal(context.Background(), domain)
	if err != nil {
		log.Printf("[sender] dkim key lookup for %s: %v", domain, err)
		return nil, false
	}
	if selector == "" || len(privKey) == 0 {
		return nil, false
	}
	signed, err := dkim.Sign(message, domain, selector, privKey)
	if err != nil {
		log.Printf("[sender] dkim sign for %s failed (sending unsigned): %v", domain, err)
		return nil, false
	}
	return signed, true
}

// normalizeAddrs parses and lowercases a list of email addresses.
// Returns an error if any address is unparseable.