diff --git a/src/modules/comment/comment.model.ts b/src/modules/comment/comment.model.ts
index 23644450..2f679eb2 100644
--- a/src/modules/comment/comment.model.ts
+++ b/src/modules/comment/comment.model.ts
@@ -60,7 +60,7 @@ export class CommentModel extends BaseModel {
   author!: string
 
   @prop({ trim: true })
-  mail?: string
+  mail: string
 
   @prop({
     trim: true,
diff --git a/src/modules/comment/comment.service.ts b/src/modules/comment/comment.service.ts
index ee7bf700..0ad5c544 100644
--- a/src/modules/comment/comment.service.ts
+++ b/src/modules/comment/comment.service.ts
@@ -232,17 +232,17 @@ export class CommentService {
         time.getMonth() + 1
       }/${time.getFullYear()}`
 
-      if (!parent || !parent.mail || !refDoc || !master.mail || !model.mail) {
+      if (!refDoc || !master.mail) {
         return
       }
 
       this.mailService.sendCommentNotificationMail({
-        to: type === ReplyMailType.Owner ? master.mail : parent.mail,
+        to: type === ReplyMailType.Owner ? master.mail : parent!.mail,
         type,
         source: {
           title: refDoc.title,
           text: model.text,
-          author: type === ReplyMailType.Guest ? parent.author : model.author,
+          author: type === ReplyMailType.Guest ? parent!.author : model.author,
           master: master.name,
           link: await this.resolveUrlByType(refType, refDoc),
           time: parsedTime,