The properties of the used .net assembly Microsoft.Dynamics.Nav.SMTP in CU 400 is very basic, e.g. applying a different Repl-To Address is not possible. For that it’s needed to go to the basics, means use the basic .net classes for Mailing. Following codeunit is a solution for that issue.

// global variablesSmtpClient, DotNet, System.Net.Mail.SmtpClient.'System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'MailMessage, DotNet, System.Net.Mail.MailMessage.'System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'OnRun()// Test the mail functions using a sample gmx mail account 'your_account@gmx.at'CreateMessage('sender name','your_account@gmx.net','your_account@gmx.net','subject','message text','reply name','replyTo@gmx.net');SendSmtpMail;CreateMessage(SenderName : Text;SenderAddress : Text;Recipients : Text;Subject : Text;Body : Text;ReplyToName : Text;ReplyToAddress : Text)// local variablesFromAddress, DotNet, System.Net.Mail.MailAddress.'System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'ReplyAddress, DotNet, System.Net.Mail.MailAddress.'System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'// create from addressFromAddress := FromAddress.MailAddress(SenderAddress, SenderName);// create mail messageIF NOT ISNULL(MailMessage) THEN  CLEAR(MailMessage);MailMessage := MailMessage.MailMessage;MailMessage.From := FromAddress;MailMessage.Body := Body;MailMessage.Subject := Subject;MailMessage."To".Clear;MailMessage."To".Add(Recipients);// create and add reply-to-addressReplyAddress := ReplyAddress.MailAddress(ReplyToAddress, ReplyToName);MailMessage.ReplyTo := ReplyAddress;SendSmtpMail()// local variablesSMTPMailSetup, Record, SMTP Mail SetupNetworkCredential, DotNet, System.Net.NetworkCredential.'System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'SMTPMailSetup.GET;WITH SMTPMailSetup DO BEGIN  SmtpClient := SmtpClient.SmtpClient("SMTP Server","SMTP Server Port");  SmtpClient.EnableSsl := "Secure Connection";  IF Authentication  Authentication::Anonymous THENIF "User ID"  '' THEN BEGIN  SmtpClient.UseDefaultCredentials := FALSE;  NetworkCredential := NetworkCredential.NetworkCredential("User ID", Password);  SmtpClient.Credentials := NetworkCredential;END ELSE BEGIN  CLEAR(NetworkCredential);  SmtpClient.Credentials := NetworkCredential;  SmtpClient.UseDefaultCredentials := TRUE;END  ELSE BEGINCLEAR(NetworkCredential);SmtpClient.Credentials := NetworkCredential;SmtpClient.UseDefaultCredentials := FALSE;  END;  IF ISNULL(MailMessage) THENERROR('Mail msg was not created');  SmtpClient.Send(MailMessage);  MailMessage.Dispose;  SmtpClient.Dispose;  CLEAR(MailMessage);  CLEAR(SmtpClient);END;

The Smtp Setup:

Mail sent result:

you can also use that codeunit for other purposes as template, e.g. for setting a different sender address.

for sending outlook mails with different reply-to address follow part 2 post of that series.

cheers