handle multiple emails in header 'To'

bot/email.go

@@ -275,7 +275,7 @@ func (e *parentEmail) fixtofrom(newSenderMailbox string, domains []string) {
 
 // Recipients returns list of recipients (to, cc)
 func (e parentEmail) Recipients() []string {
-	return append(email.AddressList(e.CC), e.To)
+	return append(email.AddressList(e.CC), strings.Split(email.Address(e.To), ",")...)
 }
 
 func (b *Bot) getParentEvent(evt *event.Event) (id.EventID, *event.Event) {

email/email.go

@@ -41,7 +41,7 @@ func New(messageID, inReplyTo, references, subject, from, to, rcptto, cc, text,
 		From:       Address(from),
 		To:         Address(to),
 		CC:         AddressList(cc),
-		RcptTo:     rcptto,
+		RcptTo:     Address(rcptto),
 		Subject:    subject,
 		Text:       text,
 		HTML:       html,

email/utils.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"net/mail"
 	"regexp"
+	"strings"
 	"time"
 
 	"maunium.net/go/mautrix/id"
@@ -26,6 +27,10 @@ func MessageID(eventID id.EventID, domain string) string {
 func Address(email string) string {
 	addr, _ := mail.ParseAddress(email) //nolint:errcheck // if it fails here, nothing will help
 	if addr == nil {
+		list := AddressList(email)
+		if len(list) > 0 {
+			return strings.Join(list, ",")
+		}
 		return email
 	}