4 files changed, 15 insertions, 5 deletions
diff --git a/internal/feed/cache_v1.go b/internal/feed/cache_v1.go
index 9a6de50..e2562c3 100644
--- a/internal/feed/cache_v1.go
+++ b/internal/feed/cache_v1.go
@@ -6,6 +6,8 @@ import (
 	"strconv"
 	"time"
 
+	"github.com/google/uuid"
+
 	"github.com/Necoro/feed2imap-go/pkg/log"
 	"github.com/Necoro/feed2imap-go/pkg/util"
 )
@@ -46,7 +48,7 @@ type cachedItem struct {
 	UpdatedDate   time.Time
 	UpdatedCache  time.Time
 	Hash          itemHash
-	ID            string
+	ID            uuid.UUID
 }
 
 func (item cachedItem) String() string {
diff --git a/internal/feed/item.go b/internal/feed/item.go
index 5c67784..b8fb7f7 100644
--- a/internal/feed/item.go
+++ b/internal/feed/item.go
@@ -1,8 +1,10 @@
 package feed
 
 import (
+	"encoding/base64"
 	"fmt"
 
+	"github.com/google/uuid"
 	"github.com/mmcdole/gofeed"
 
 	"github.com/Necoro/feed2imap-go/pkg/config"
@@ -22,7 +24,7 @@ type item struct {
 	updateOnly bool
 	reasons    []string
 	images     []feedImage
-	itemId     string
+	itemId     uuid.UUID
 }
 
 // Creator returns the name of the creating author.
@@ -54,6 +56,11 @@ func (item *item) defaultEmail() string {
 	return item.feed.Global.DefaultEmail
 }
 
+func (item *item) id() string {
+	idStr := base64.RawURLEncoding.EncodeToString(item.itemId[:])
+	return item.feed.cached.ID() + "#" + idStr
+}
+
 func (item *item) messageId() string {
-	return fmt.Sprintf("<feed#%s#%s@%s>", item.feed.cached.ID(), item.itemId, config.Hostname())
+	return fmt.Sprintf("<feed#%s@%s>", item.id(), config.Hostname())
 }
diff --git a/internal/feed/mail.go b/internal/feed/mail.go
index 41a4cbd..8bb9846 100644
--- a/internal/feed/mail.go
+++ b/internal/feed/mail.go
@@ -55,6 +55,7 @@ func (item *item) buildHeader() message.Header {
 	h.SetAddressList("To", item.toAddress())
 	h.Set("X-Feed2Imap-Version", config.Version())
 	h.Set("X-Feed2Imap-Reason", strings.Join(item.reasons, ","))
+	h.Set("X-Feed2Imap-Item", item.id())
 	h.Set("Message-Id", item.messageId())
 
 	{ // date
diff --git a/internal/feed/parse.go b/internal/feed/parse.go
index dfb447a..1ba90fd 100644
--- a/internal/feed/parse.go
+++ b/internal/feed/parse.go
@@ -7,7 +7,7 @@ import (
 	"net/http"
 	"time"
 
-	"github.com/lithammer/shortuuid"
+	"github.com/google/uuid"
 	"github.com/mmcdole/gofeed"
 
 	"github.com/Necoro/feed2imap-go/pkg/log"
@@ -56,7 +56,7 @@ func (feed *Feed) parse() error {
 	feed.feed = parsedFeed
 	feed.items = make([]item, len(parsedFeed.Items))
 	for idx, feedItem := range parsedFeed.Items {
-		feed.items[idx] = item{Feed: parsedFeed, Item: feedItem, itemId: shortuuid.New(), feed: feed}
+		feed.items[idx] = item{Feed: parsedFeed, Item: feedItem, itemId: uuid.New(), feed: feed}
 	}
 	return nil
 }