Augment post details with recipient information

src/internal/m365/collection/groups/conversation_handler.go

@@ -19,15 +19,19 @@ var _ backupHandler[models.Conversationable, models.Postable] = &conversationsBa
 type conversationsBackupHandler struct {
 	ac                api.Conversations
 	protectedResource string
+	// SMTP address for the group
+	resourceEmail string
 }
 
 func NewConversationBackupHandler(
 	protectedResource string,
 	ac api.Conversations,
+	email string,
 ) conversationsBackupHandler {
 	return conversationsBackupHandler{
 		ac:                ac,
 		protectedResource: protectedResource,
+		resourceEmail:     email,
 	}
 }
 
@@ -134,6 +138,13 @@ func (bh conversationsBackupHandler) augmentItemInfo(
 	dgi *details.GroupsInfo,
 	c models.Conversationable,
 ) {
+	// Posts are always sent to the group email address, along with additional
+	// recipients if any. Currently, we don't have a way to get the unique
+	// recipient list for individual posts due to graph api limitations.
+	//
+	// Store the group mail address so that we can use it to populate the 'To'
+	// field during Post -> EML exports.
+	dgi.Post.Recipients = []string{bh.resourceEmail}
 	dgi.Post.Topic = ptr.Val(c.GetTopic())
 }
 

src/internal/m365/service/groups/backup.go

@@ -3,6 +3,7 @@ package groups
 import (
 	"context"
 	"fmt"
+	"strings"
 
 	"github.com/alcionai/clues"
 	"github.com/kopia/kopia/repo/manifest"
@@ -319,10 +320,18 @@ func backupConversations(
 	counter *count.Bus,
 	errs *fault.Bus,
 ) ([]data.BackupCollection, error) {
+	groupEmail := strings.Clone(ptr.Val(bc.group.GetMail()))
+	// This is unlikely, but if it does happen in the wild, we should investigate it.
+	if len(groupEmail) == 0 {
+		return nil, clues.New("group has no mail address")
+	}
+
 	var (
 		bh = groups.NewConversationBackupHandler(
 			bc.producerConfig.ProtectedResource.ID(),
-			bc.apiCli.Conversations())
+			bc.apiCli.Conversations(),
+			groupEmail,
+		)
 		colls []data.BackupCollection
 	)
 

src/pkg/backup/details/groups.go

@@ -61,11 +61,12 @@ type GroupsInfo struct {
 }
 
 type ConversationPostInfo struct {
-	CreatedAt time.Time `json:"createdAt,omitempty"`
-	Creator   string    `json:"creator,omitempty"`
-	Preview   string    `json:"preview,omitempty"`
-	Size      int64     `json:"size,omitempty"`
-	Topic     string    `json:"topic,omitempty"`
+	CreatedAt  time.Time `json:"createdAt,omitempty"`
+	Creator    string    `json:"creator,omitempty"`
+	Preview    string    `json:"preview,omitempty"`
+	Recipients []string  `json:"recipients,omitempty"`
+	Size       int64     `json:"size,omitempty"`
+	Topic      string    `json:"topic,omitempty"`
 }
 
 type ChannelMessageInfo struct {