bridge thread replies from matrix to email

README.md

@@ -35,7 +35,7 @@ so you can use it to send emails from your apps and scripts as well.
 - [x] SMTP client
 - [x] SMTP server (you can use Postmoogle as general purpose SMTP server to send emails from your scripts or apps)
 - [x] Send a message to matrix room with special format to send a new email, even to multiple email addresses at once
-- [ ] Reply to matrix thread sends reply into email thread
+- [x] Reply to matrix thread sends reply into email thread
 
 ## Configuration
 

bot/command.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"maunium.net/go/mautrix/event"
+	"maunium.net/go/mautrix/format"
 	"maunium.net/go/mautrix/id"
 
 	"gitlab.com/etke.cc/postmoogle/utils"
@@ -359,20 +360,49 @@ func (b *Bot) runSend(ctx context.Context) {
 		}
 	}
 
+	b.lock(evt.RoomID)
+	defer b.unlock(evt.RoomID)
+
 	from := mailbox + "@" + b.domains[0]
 	ID := fmt.Sprintf("<%s@%s>", evt.ID, b.domains[0])
 	for _, to := range tos {
-		data := utils.
+		email := utils.NewEmail(ID, "", subject, from, to, body, "", nil)
-			NewEmail(ID, "", subject, from, to, body, "", nil).
+		data := email.Compose(b.getBotSettings().DKIMPrivateKey())
-			Compose(b.getBotSettings().DKIMPrivateKey())
 		err = b.sendmail(from, to, data)
 		if err != nil {
 			b.Error(ctx, evt.RoomID, "cannot send email to %s: %v", to, err)
 		} else {
-			b.SendNotice(ctx, evt.RoomID, "Email has been sent to "+to)
+			b.forgeSentMetadata(ctx, email, &cfg)
 		}
 	}
 	if len(tos) > 1 {
 		b.SendNotice(ctx, evt.RoomID, "All emails were sent.")
 	}
 }
+
+// forgeSentMetadata used to save metadata from !pm sent event to a separate notice message
+// because that metadata is needed to determine email thread relations
+func (b *Bot) forgeSentMetadata(ctx context.Context, email *utils.Email, cfg *roomSettings) {
+	evt := eventFromContext(ctx)
+	threadID := utils.EventParent(evt.ID, evt.Content.AsMessage())
+	content := email.Content(threadID, cfg.ContentOptions())
+	notice := format.RenderMarkdown("Email has been sent to "+email.To, true, true)
+	notice.MsgType = event.MsgNotice
+	msgContent, ok := content.Parsed.(event.MessageEventContent)
+	if !ok {
+		b.Error(ctx, evt.RoomID, "cannot parse message")
+		return
+	}
+	msgContent.Body = notice.Body
+	msgContent.FormattedBody = notice.FormattedBody
+	content.Parsed = msgContent
+	msgID, err := b.lp.Send(evt.RoomID, &content)
+	if err != nil {
+		b.Error(ctx, evt.RoomID, "cannot parse message")
+		return
+	}
+	if threadID != "" {
+		b.setThreadID(evt.RoomID, fmt.Sprintf("<%s@%s>", msgID, b.domains[0]), threadID)
+	}
+	b.setLastEventID(evt.RoomID, threadID, msgID)
+}

bot/email.go

@@ -3,7 +3,6 @@ package bot
 import (
 	"context"
 	"errors"
-	"fmt"
 	"strings"
 
 	"maunium.net/go/mautrix/event"
@@ -24,6 +23,7 @@ const (
 	eventInReplyToKey = "cc.etke.postmoogle.inReplyTo"
 	eventSubjectKey   = "cc.etke.postmoogle.subject"
 	eventFromKey      = "cc.etke.postmoogle.from"
+	eventToKey        = "cc.etke.postmoogle.to"
 )
 
 // SetSendmail sets mail sending func to the bot
@@ -81,14 +81,14 @@ func (b *Bot) IncomingEmail(ctx context.Context, email *utils.Email) error {
 	if !ok {
 		return errors.New("room not found")
 	}
-	b.lock(roomID)
-	defer b.unlock(roomID)
-
 	cfg, err := b.getRoomSettings(roomID)
 	if err != nil {
 		b.Error(ctx, roomID, "cannot get settings: %v", err)
 	}
 
+	b.lock(roomID)
+	defer b.unlock(roomID)
+
 	var threadID id.EventID
 	if email.InReplyTo != "" && !cfg.NoThreads() {
 		threadID = b.getThreadID(roomID, email.InReplyTo)
@@ -115,27 +115,28 @@ func (b *Bot) IncomingEmail(ctx context.Context, email *utils.Email) error {
 	return nil
 }
 
-func (b *Bot) getParentEmail(evt *event.Event) (string, string, string) {
+func (b *Bot) getParentEmail(evt *event.Event) (string, string, string, string) {
 	content := evt.Content.AsMessage()
 	parentID := utils.EventParent(evt.ID, content)
 	if parentID == evt.ID {
-		return "", "", ""
+		return "", "", "", ""
 	}
 	parentID = b.getLastEventID(evt.RoomID, parentID)
 	parentEvt, err := b.lp.GetClient().GetEvent(evt.RoomID, parentID)
 	if err != nil {
 		b.log.Error("cannot get parent event: %v", err)
-		return "", "", ""
+		return "", "", "", ""
 	}
 	if parentEvt.Content.Parsed == nil {
 		perr := parentEvt.Content.ParseRaw(event.EventMessage)
 		if perr != nil {
 			b.log.Error("cannot parse event content: %v", perr)
-			return "", "", ""
+			return "", "", "", ""
 		}
 	}
 
-	to := utils.EventField[string](&parentEvt.Content, eventFromKey)
+	from := utils.EventField[string](&parentEvt.Content, eventFromKey)
+	to := utils.EventField[string](&parentEvt.Content, eventToKey)
 	inReplyTo := utils.EventField[string](&parentEvt.Content, eventMessageIDkey)
 	if inReplyTo == "" {
 		inReplyTo = parentID.String()
@@ -148,49 +149,55 @@ func (b *Bot) getParentEmail(evt *event.Event) (string, string, string) {
 		subject = strings.SplitN(content.Body, "\n", 1)[0]
 	}
 
-	return to, inReplyTo, subject
+	return from, to, inReplyTo, subject
 }
 
-// Send2Email sends message to email
+// SendEmailReply sends replies from matrix thread to email thread
-// TODO rewrite to thread replies only
+func (b *Bot) SendEmailReply(ctx context.Context) {
-func (b *Bot) SendEmailReply(ctx context.Context, to, subject, body string) error {
 	var inReplyTo string
 	evt := eventFromContext(ctx)
 	cfg, err := b.getRoomSettings(evt.RoomID)
 	if err != nil {
-		return err
+		b.Error(ctx, evt.RoomID, "cannot retrieve room settings: %v", err)
+		return
 	}
 	mailbox := cfg.Mailbox()
 	if mailbox == "" {
-		return fmt.Errorf("mailbox not configured, kupo")
+		b.Error(ctx, evt.RoomID, "mailbox is not configured, kupo")
+		return
 	}
-	from := mailbox + "@" + b.domains[0]
+
-	pTo, pInReplyTo, pSubject := b.getParentEmail(evt)
+	b.lock(evt.RoomID)
-	inReplyTo = pInReplyTo
+	defer b.unlock(evt.RoomID)
-	if pTo != "" && to == "" {
+	fromMailbox := mailbox + "@" + b.domains[0]
-		to = pTo
+	from, to, inReplyTo, subject := b.getParentEmail(evt)
+	// when email was sent from matrix and reply was sent from matrix again
+	if fromMailbox != from {
+		to = from
 	}
-	if pSubject != "" && subject == "" {
+
-		subject = pSubject
+	if to == "" {
+		b.Error(ctx, evt.RoomID, "cannot find parent email and continue the thread. Please, start a new email thread")
+		return
 	}
 
 	content := evt.Content.AsMessage()
 	if subject == "" {
 		subject = strings.SplitN(content.Body, "\n", 1)[0]
 	}
-	if body == "" {
+	body := content.Body
-		if content.FormattedBody != "" {
-			body = content.FormattedBody
-		} else {
-			body = content.Body
-		}
-	}
 
 	ID := evt.ID.String()[1:] + "@" + b.domains[0]
+	b.log.Debug("send email reply ID=%s from=%s to=%s inReplyTo=%s subject=%s body=%s", ID, from, to, inReplyTo, subject, body)
 	data := utils.
 		NewEmail(ID, inReplyTo, subject, from, to, body, "", nil).
 		Compose(b.getBotSettings().DKIMPrivateKey())
-	return b.sendmail(from, to, data)
+
+	err = b.sendmail(from, to, data)
+	if err != nil {
+		b.Error(ctx, evt.RoomID, "cannot send email: %v", err)
+		return
+	}
 }
 
 func (b *Bot) sendFiles(ctx context.Context, roomID id.RoomID, files []*utils.File, noThreads bool, parentID id.EventID) {

bot/message.go

@@ -20,6 +20,9 @@ func (b *Bot) handle(ctx context.Context) {
 	message := strings.TrimSpace(content.Body)
 	cmd := b.parseCommand(message, true)
 	if cmd == nil {
+		if content.RelatesTo != nil {
+			b.SendEmailReply(ctx)
+		}
 		return
 	}
 

bot/settings_room.go

@@ -146,6 +146,7 @@ func (s roomSettings) ContentOptions() *utils.ContentOptions {
 		Subject:   !s.NoSubject(),
 		Threads:   !s.NoThreads(),
 
+		ToKey:        eventToKey,
 		FromKey:      eventFromKey,
 		SubjectKey:   eventSubjectKey,
 		MessageIDKey: eventMessageIDkey,

utils/email.go

@@ -48,6 +48,7 @@ type ContentOptions struct {
 	InReplyToKey string
 	SubjectKey   string
 	FromKey      string
+	ToKey        string
 }
 
 // AddressValid checks if email address is valid
@@ -122,6 +123,7 @@ func (e *Email) Content(threadID id.EventID, options *ContentOptions) *event.Con
 			options.InReplyToKey: e.InReplyTo,
 			options.SubjectKey:   e.Subject,
 			options.FromKey:      e.From,
+			options.ToKey:        e.To,
 		},
 		Parsed: parsed,
 	}