diff --git a/AMESCoreStudio.WebApi/Models/BAS/MailGroup.cs b/AMESCoreStudio.WebApi/Models/BAS/MailGroup.cs
index e2426353..a6fa09aa 100644
--- a/AMESCoreStudio.WebApi/Models/BAS/MailGroup.cs
+++ b/AMESCoreStudio.WebApi/Models/BAS/MailGroup.cs
@@ -27,7 +27,7 @@ namespace AMESCoreStudio.WebApi.Models.BAS
         [DataMember]
         [Display(Name = "MAIL群組名稱")]
         [Required(ErrorMessage = "{0},不能空白")]
-        [StringLength(10, ErrorMessage = "{0},不能大于{1}")]
+        [StringLength(50, ErrorMessage = "{0},不能大于{1}")]
         public string GroupNo { get; set; }
 
         /// <summary>