diff --git a/backend/00-router.go b/backend/00-router.go
index d659dea..ec04817 100644
--- a/backend/00-router.go
+++ b/backend/00-router.go
@@ -1,11 +1,13 @@
 package backend
 
 import (
+	"bytes"
 	"database/sql"
 	"errors"
 	"fmt"
 	"html"
 	"net/http"
+	"net/mail"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -39,6 +41,8 @@ func RegisterRoutes(mux *http.ServeMux) {
 	mux.HandleFunc("/transfer", transferHandler)
 	mux.HandleFunc("/transfer/", transferHandler)
 	mux.HandleFunc("/boxes/source", emailBoxHandler)
+	mux.HandleFunc("/boxes/source/messages", sourceMailboxMessagesHandler)
+	mux.HandleFunc("/boxes/source/message", sourceMailboxMessageHandler)
 	mux.HandleFunc("/boxes/target", emailBoxHandler)
 	mux.HandleFunc("/migrate/run", migrateRunHandler)       // TODO Codex: RunMigration im Hintergrund
 	mux.HandleFunc("/migrate/status", migrateStatusHandler) // TODO Codex: jobs-Fortschritt (HTMX-Poll)
@@ -314,6 +318,63 @@ func emailBoxHandler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func sourceMailboxMessagesHandler(w http.ResponseWriter, r *http.Request) {
+	accountName := strings.TrimSpace(r.URL.Query().Get("source"))
+	folder := strings.TrimSpace(r.URL.Query().Get("folder"))
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	if accountName == "" || folder == "" {
+		fmt.Fprint(w, `<div class="pane-head">Nachrichten</div><div class="ef-empty">Quell-Postfach und Ordner waehlen.</div>`)
+		return
+	}
+	account, err := GetAccount(accountName)
+	if err != nil {
+		fmt.Fprintf(w, `<div class="pane-head">Nachrichten</div><div class="ef-empty">%s</div>`, html.EscapeString(err.Error()))
+		return
+	}
+	messages, err := fetchSourceFolderMessages(account, folder)
+	if err != nil {
+		fmt.Fprintf(w, `<div class="pane-head">Nachrichten</div><div class="ef-empty">%s</div>`, html.EscapeString(err.Error()))
+		return
+	}
+	renderSourceMailboxMessageList(w, account, folder, messages)
+}
+
+func sourceMailboxMessageHandler(w http.ResponseWriter, r *http.Request) {
+	accountName := strings.TrimSpace(r.URL.Query().Get("source"))
+	folder := strings.TrimSpace(r.URL.Query().Get("folder"))
+	index, err := strconv.Atoi(r.URL.Query().Get("index"))
+	if err != nil {
+		http.Error(w, "bad index", http.StatusBadRequest)
+		return
+	}
+	account, err := GetAccount(accountName)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	messages, err := fetchSourceFolderMessages(account, folder)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+	if index < 0 || index >= len(messages) {
+		http.Error(w, "message index out of range", http.StatusNotFound)
+		return
+	}
+	raw := messages[index].Body
+	msg, err := mail.ReadMessage(bytes.NewReader(raw))
+	if err != nil {
+		renderReadPaneWithSource(w, account.Name, folder, "", index, "(unlesbar)", "", "", string(raw))
+		return
+	}
+	renderReadPaneWithSource(w, account.Name, folder, "", index,
+		decodeHeader(msg.Header.Get("Subject")),
+		decodeHeader(msg.Header.Get("From")),
+		decodeHeader(msg.Header.Get("Date")),
+		messageBody(raw),
+	)
+}
+
 func archiveCreateHandler(w http.ResponseWriter, r *http.Request) {
 	if !requireManager(w, r) {
 		return
@@ -920,8 +981,50 @@ func renderSourceFolders(b *strings.Builder, account Account) {
 		return
 	}
 	for _, folder := range folders {
-		fmt.Fprintf(b, `<div class="tree-node folder"><span class="tree-label">%s</span><span class="tree-count">%s</span></div>`,
-			html.EscapeString(folder.Name), html.EscapeString(strings.Join(folder.Attrs, " ")))
+		fmt.Fprintf(b, `<a class="tree-node folder" href="#" hx-get="/boxes/source/messages?source=%s&amp;folder=%s" hx-target="#list" hx-swap="innerHTML"><span class="tree-label">%s</span><span class="tree-count">%s</span></a>`,
+			urlEsc(account.Name), urlEsc(folder.Name), html.EscapeString(folder.Name), html.EscapeString(strings.Join(folder.Attrs, " ")))
+	}
+}
+
+func fetchSourceFolderMessages(account Account, folder string) ([]RawMessage, error) {
+	if accountProto(account) == "pop3" {
+		src, err := OpenPOP3Source(account)
+		if err != nil {
+			return nil, err
+		}
+		defer src.Close()
+		return src.Fetch(folder)
+	}
+	src, err := OpenIMAPSource(account)
+	if err != nil {
+		return nil, err
+	}
+	defer src.Close()
+	return src.Fetch(folder)
+}
+
+func renderSourceMailboxMessageList(w http.ResponseWriter, account Account, folder string, messages []RawMessage) {
+	fmt.Fprintf(w, `<div class="pane-head">%s / %s (%d)</div>`, html.EscapeString(account.SrcUser), html.EscapeString(folder), len(messages))
+	for i, raw := range messages {
+		subject := "(ohne Betreff)"
+		from := "(ohne Absender)"
+		date := ""
+		if msg, err := mail.ReadMessage(bytes.NewReader(raw.Body)); err == nil {
+			if v := decodeHeader(msg.Header.Get("Subject")); v != "" {
+				subject = v
+			}
+			if v := decodeHeader(msg.Header.Get("From")); v != "" {
+				from = v
+			}
+			date = decodeHeader(msg.Header.Get("Date"))
+		}
+		fmt.Fprintf(w, `<a class="msg-row" href="#" draggable="true" data-source="%s" data-folder="%s" data-index="%d" hx-get="/boxes/source/message?source=%s&amp;folder=%s&amp;index=%d" hx-target="#read" hx-swap="innerHTML"><span class="msg-from">%s</span><span class="msg-subject">%s</span><span class="msg-date">%s</span></a>`,
+			html.EscapeString(account.Name), html.EscapeString(folder), i,
+			urlEsc(account.Name), urlEsc(folder), i,
+			html.EscapeString(from), html.EscapeString(subject), html.EscapeString(date))
+	}
+	if len(messages) == 0 {
+		fmt.Fprint(w, `<div class="ef-empty">Keine Nachrichten in diesem Quell-Ordner.</div>`)
 	}
 }