diff --git a/src/Core/Models/Api/Request/GroupRequestModel.cs b/src/Core/Models/Api/Request/GroupRequestModel.cs
index c491647123..3d0efff23c 100644
--- a/src/Core/Models/Api/Request/GroupRequestModel.cs
+++ b/src/Core/Models/Api/Request/GroupRequestModel.cs
@@ -13,6 +13,7 @@ namespace Bit.Core.Models.Api
         public string Name { get; set; }
         [Required]
         public bool? AccessAll { get; set; }
+        [StringLength(300)]
         public string ExternalId { get; set; }
         public IEnumerable<SelectionReadOnlyRequestModel> Collections { get; set; }
 
diff --git a/src/Core/Models/Api/Request/InstallationRequestModel.cs b/src/Core/Models/Api/Request/InstallationRequestModel.cs
index ddf94d4e87..5b27281490 100644
--- a/src/Core/Models/Api/Request/InstallationRequestModel.cs
+++ b/src/Core/Models/Api/Request/InstallationRequestModel.cs
@@ -7,6 +7,7 @@ namespace Bit.Core.Models.Api
     {
         [Required]
         [EmailAddress]
+        [StringLength(50)]
         public string Email { get; set; }
 
         public Installation ToInstallation()
diff --git a/src/Core/Models/Api/Request/Organizations/ImportOrganizationUsersRequestModel.cs b/src/Core/Models/Api/Request/Organizations/ImportOrganizationUsersRequestModel.cs
index 1178590bf3..33ba7455e5 100644
--- a/src/Core/Models/Api/Request/Organizations/ImportOrganizationUsersRequestModel.cs
+++ b/src/Core/Models/Api/Request/Organizations/ImportOrganizationUsersRequestModel.cs
@@ -14,8 +14,10 @@ namespace Bit.Core.Models.Api
         public class Group
         {
             [Required]
+            [StringLength(100)]
             public string Name { get; set; }
             [Required]
+            [StringLength(300)]
             public string ExternalId { get; set; }
             public IEnumerable<string> Users { get; set; }
 
@@ -39,9 +41,11 @@ namespace Bit.Core.Models.Api
         public class User : IValidatableObject
         {
             [EmailAddress]
+            [StringLength(50)]
             public string Email { get; set; }
             public bool Deleted { get; set; }
             [Required]
+            [StringLength(300)]
             public string ExternalId { get; set; }
 
             public ImportedOrganizationUser ToImportedOrganizationUser()
diff --git a/src/Core/Models/Api/Request/Organizations/OrganizationUserRequestModels.cs b/src/Core/Models/Api/Request/Organizations/OrganizationUserRequestModels.cs
index 01eeb44b7e..2c87bb93ee 100644
--- a/src/Core/Models/Api/Request/Organizations/OrganizationUserRequestModels.cs
+++ b/src/Core/Models/Api/Request/Organizations/OrganizationUserRequestModels.cs
@@ -28,12 +28,17 @@ namespace Bit.Core.Models.Api
             }
 
             var attr = new EmailAddressAttribute();
-            for(int i = 0; i < Emails.Count(); i++)
+            for(var i = 0; i < Emails.Count(); i++)
             {
-                if(!attr.IsValid(Emails.ElementAt(i)))
+                var email = Emails.ElementAt(i);
+                if(!attr.IsValid(email))
                 {
                     yield return new ValidationResult($"Email #{i + 1} is not valid.", new string[] { nameof(Emails) });
                 }
+                else if(email.Length > 50)
+                {
+                    yield return new ValidationResult($"Email #{i + 1} is longer than 50 characters.", new string[] { nameof(Emails) });
+                }
             }
         }
     }