SMTP Server Authentication the Server Response was 5. Authentication required in gmail ASP. NET C MVC EF Cloud SQL Server IIS. Support Message Rejected with SMTP Code 554. SMTP Code 554. 5. Recipient. or is not authorized with the authentication used. Error The SMTP server requires a secure connection or the client was not authenticated. The server response was 5. Authentication Required. Its a. But I dont see why I would be able to send emails through gmails SMTP in ASP. NET but not with Database Mail. Authentication Required. Setting Email in NopCommerce 2. Reply. Liz. smtp. Port 587. 5. 5. 1 Authentication Required. Smtp Authentication TestI was working on MVC C application sending email through Gmail Server, meanwhile popped up me issue the server response was 5. So we required action to set on security issue which is default off in Gmail Email settings. I have published an article on How to send SMS using C, now a days it has become very necessary to integrate SMS API into our application. Error Description. An exception of type System. Net. Mail. Smtp. Exception occurred in System. Additional information The SMTP server requires a secure connection or the client was not authenticated. The server response was 5. Smtp 5.5.1 Authentication' title='Smtp 5.5.1 Authentication' />Authentication Required. Gmail Code Snippet. Below is the code snippet using to send Email through Gmail Host Http. Post. public Json. Result Send. Emailstring name, string phone, string email, string description. ID youtemailgmail. Password demo1. Email Sent Successfully. Java Program To Convert Ascii To Decimal. Phone phone. Mail. Message mail new Mail. Message. mail. To. Fnaf 1 Full Pcgames. Addsender. ID. mail. From new Mail. Addresssender. Northern Lights Pullman Ebook. ID. mail. Subject My Test Email. Body body. mail. Is. Body. Html true. Smtp. Client smtp new Smtp. Client. smtp. Host smtp. Or Your SMTP Server Address. Credentials new System. Net. Network. Credentialsender. ID, sender. Password. Port 5. 87. smtp. Enable. Ssl true. Sendmail. catch Exception ex. Smtp authentification required. You need to tell the SMTP client that you will not be using your windows credentials to. Authentication Required 2. SMTP Error 5. 5. 1, username, password correct, ssl. AUTHENTICATION. SMTP. Response. WriteException in send. Email ex. Message. Jsonresult. First login into Gmail Account from which Gmail credentials are you using to send email. Now go to Gmail Settings Feature, it comes in your Gmail Inbox on right side, as you see in picture below. Move to Security Feature. Access for less secure apps. Turn off default Turn On. Click on Turn On option to authorize emails sending through while programming MVC, C, PHP, Java etc. Gmail account. Above will help to resolve issue the server response was 5. Gmail credentials in programming languages like ASP. Net, MVC, C, PHP, Java etc.