diff --git a/src/Core/Models/Domain/UsernameGenerationOptions.cs b/src/Core/Models/Domain/UsernameGenerationOptions.cs
index 554783b66..2ca57083e 100644
--- a/src/Core/Models/Domain/UsernameGenerationOptions.cs
+++ b/src/Core/Models/Domain/UsernameGenerationOptions.cs
@@ -46,7 +46,11 @@ namespace Bit.Core.Models.Domain
                 case ForwardedEmailServiceType.DuckDuckGo:
                     return new ForwarderOptions { ApiKey = DuckDuckGoApiKey };
                 case ForwardedEmailServiceType.Fastmail:
-                    return new ForwarderOptions { ApiKey = FastMailApiKey };
+                    return new FastmailForwarderOptions
+                    {
+                        ApiKey = FastMailApiKey,
+                        Website = EmailWebsite
+                    };
                 case ForwardedEmailServiceType.FirefoxRelay:
                     return new ForwarderOptions { ApiKey = FirefoxRelayApiAccessToken };
                 case ForwardedEmailServiceType.SimpleLogin:
diff --git a/src/Core/Services/EmailForwarders/FastmailForwarder.cs b/src/Core/Services/EmailForwarders/FastmailForwarder.cs
index a47229861..7380fd0fc 100644
--- a/src/Core/Services/EmailForwarders/FastmailForwarder.cs
+++ b/src/Core/Services/EmailForwarders/FastmailForwarder.cs
@@ -9,16 +9,21 @@ using Newtonsoft.Json.Linq;
 
 namespace Bit.Core.Services.EmailForwarders
 {
-    public class FastmailForwarder : BaseForwarder<ForwarderOptions>
+    public class FastmailForwarderOptions : ForwarderOptions
+    {
+        public string Website { get; set; }
+    }
+
+    public class FastmailForwarder : BaseForwarder<FastmailForwarderOptions>
     {
         protected override string RequestUri => "https://api.fastmail.com/jmap/api/";
 
-        protected override void ConfigureHeaders(HttpRequestHeaders headers, ForwarderOptions options)
+        protected override void ConfigureHeaders(HttpRequestHeaders headers, FastmailForwarderOptions options)
         {
             headers.Add("Authorization", $"Bearer {options.ApiKey}");
         }
 
-        protected override async Task<HttpContent> GetContentAsync(IApiService apiService, ForwarderOptions options)
+        protected override async Task<HttpContent> GetContentAsync(IApiService apiService, FastmailForwarderOptions options)
         {
             string accountId = null;
             try
@@ -55,7 +60,8 @@ namespace Bit.Core.Services.EmailForwarders
                                         ["state"] = "enabled",
                                         ["description"] = "",
                                         ["url"] = "",
-                                        ["emailPrefix"] = ""
+                                        ["emailPrefix"] = "",
+                                        ["forDomain"] = options.Website ?? ""
                                     }
                                 }
                             },
diff --git a/src/Core/Services/UsernameGenerationService.cs b/src/Core/Services/UsernameGenerationService.cs
index 5789dac5c..2ed5454fe 100644
--- a/src/Core/Services/UsernameGenerationService.cs
+++ b/src/Core/Services/UsernameGenerationService.cs
@@ -148,6 +148,13 @@ namespace Bit.Core.Services
                                     .GenerateAsync(_apiService, forwardedEmailOptions);
             }
 
+            if (options.ServiceType == ForwardedEmailServiceType.Fastmail)
+            {
+                var fastmailEmailOptions = (FastmailForwarderOptions)options.GetForwarderOptions();
+                return await new FastmailForwarder()
+                                    .GenerateAsync(_apiService, fastmailEmailOptions);
+            }
+
             BaseForwarder<ForwarderOptions> simpleForwarder = null;
 
             switch (options.ServiceType)
@@ -161,9 +168,6 @@ namespace Bit.Core.Services
                 case ForwardedEmailServiceType.DuckDuckGo:
                     simpleForwarder = new DuckDuckGoForwarder();
                     break;
-                case ForwardedEmailServiceType.Fastmail:
-                    simpleForwarder = new FastmailForwarder();
-                    break;
                 default:
                     _logger.Value.Error($"Error UsernameGenerationService: ForwardedEmailServiceType {options.ServiceType} not implemented.");
                     return Constants.DefaultUsernameGenerated;