https://www.aras.com/community/f/development/3960/mailbox-unavailableHello, I use the following code to send mail in Server Method of Wrokflow Activity.I have done IIS SMTP Email Configuration. System.Net.Mail.MailAddress SendFrom = new System.Net.Mail.MailAddress(from_user, from_userN); System.Net.Mail.MailAddress SendToja-JPTelligent Community 12https://www.aras.com/community/thread/2129?ContentTypeID=1Tue, 09 Oct 2018 09:14:04 GMT916d3f7e-8ddc-42f8-8d45-380822f51406:d24fd73d-5286-4293-b551-08c6b7525e98Christopher GillisHi Chan, The error appears to be coming from your mail server rather than the Innovator server. It seems like the email being sent from the Innovator Server is being blocked by your spam filter, so I&#39;d recommend adding your Innovator server to the whitelist of your SMTP server. Because this isn&#39;t an Innovator-specific issue, you may have better luck posting this question on a more general forum like Stack Overflow. Chris <hr /> Christopher Gillis Aras Labs Software Engineer<div style="clear:both;"></div>