diff --git a/IRaCIS.Core.Application/Service/Common/MailService.cs b/IRaCIS.Core.Application/Service/Common/MailService.cs
index 7c283a183..665d2dc4f 100644
--- a/IRaCIS.Core.Application/Service/Common/MailService.cs
+++ b/IRaCIS.Core.Application/Service/Common/MailService.cs
@@ -471,7 +471,7 @@ namespace IRaCIS.Core.Application.Service
                     trialInfo.ExperimentName,
                     trialInfo.ResearchProgramNo,
                     trialInfo.TrialCode,
-                    sysUserInfo.EMail,
+                    sysUserInfo.IsFirstAdd ? sysUserInfo.EMail : sysUserInfo.UserName,
                     userTypes,
                      sysUserInfo.IsFirstAdd ? redirectUrl : baseUrl
                     );
@@ -533,7 +533,7 @@ namespace IRaCIS.Core.Application.Service
                     trialInfo.ExperimentName,
                     trialInfo.ResearchProgramNo,
                     trialInfo.TrialCode,
-                    sysUserInfo.EMail,
+                    sysUserInfo.IsFirstAdd ? sysUserInfo.EMail : sysUserInfo.UserName,
                     userTypes,
                     sysUserInfo.IsFirstAdd ? redirectUrl : baseUrl
                     );
@@ -665,7 +665,7 @@ namespace IRaCIS.Core.Application.Service
                     trialInfo.ExperimentName,
                     trialInfo.ResearchProgramNo,
                     trialInfo.TrialCode,
-                    sysUserInfo.UserName,
+                    sysUserInfo.IsFirstAdd ? sysUserInfo.EMail : sysUserInfo.UserName,
                     $"{userType.UserTypeShortName} ({userType.UserTypeName})",
                     sysUserInfo.IsFirstAdd ? redirectUrl : baseUrl
                     );