Set clientDomain in SmtpClient

[olmobrutall]

(moved from dotnet/core#2031)

The old implementation of SmtpClient (https://referencesource.microsoft.com/#system/net/System/Net/mail/SmtpClient.cs) was able to use the clientDomain from configuration MailConfiguration.Smtp.Network.ClientDomain;

  <smtp>
     <network host="somehost" port="25" clientDomain="mymachine.mydomain.com" enableSsl="false" />
  </smtp>

solving problems like this one: https://stackoverflow.com/questions/37410598/fqdn-with-smtpclient-in-powershell

But in the .Net Core implementation https://github.com/dotnet/corefx/blob/master/src/System.Net.Mail/src/System/Net/Mail/SmtpClient.cs only the fallback to IPGlobalProperties.GetIPGlobalProperties().HostName; is implemented.

Unfortunately, I get a SmtpException because my Smtp server requires fully-qualified hostnames:

Maybe we can find a solution by changing the SMTP server, but our admins say that FQDN check is a POSTFIX default setting, so I'm surprised I'm the only one having this problem.

Thanks

[karelz]

You are apparently the first one to need it (or at least to say so here on our repo). I haven't seen any other issue filed to request that.
We consider SmtpClient legacy API and we do not plan significant investments in it. Our recommendation is to use MailKit or other community solutions instead - see platform-compat rule and Networking roadmap.

That said. If it is important to you and if the implementation is straightforward, we would be likely ok to take a PR.

[karelz]

Triage: It may require new API actually.

Only 1 upvote in 1 year, no takers to implement it -- closing.