确保用户名和密码在行中正确无误：

Make sure the username and password is correct in the line:

smtp.Credentials = new System.Net.NetworkCredential("computersaddict.himanshu@gmail.com", "password");

尝试评论该行：

try commenting the line :

smtp.UseDefaultCredentials = false;

还尝试在构造函数外部设置属性：

Also try setting the properties outside the constructor:

smtp.Host = "smtp.gmail.com";
smtp.Port = 587;

按照以下步骤检查解决方案1 ​​。



1） https://accounts.google.com/DisplayUnlockCaptcha [ ^ ] //点击允许访问您的Google帐户



2）你必须为你的谷歌帐户启用从其他时区/ IP登录。



这样做是按照链接 https://g.co/allowaccess [ ^ ]并允许通过单击继续按钮进行访问。



3）转到以下链接的安全设置 https://www.google.com/ settings / security / lesssecureapps [ ^ ]和启用不太安全的应用。这样您就可以从所有应用程序登录。

Hi,

Check the solution 1 after follow this below steps.

1) https://accounts.google.com/DisplayUnlockCaptcha[^] //Click allow access to your Google account

2) You have to enable login from other timezone / ip for your google account.

to do this follow the link https://g.co/allowaccess[^] and allow access by clicking the continue button.

3) go to security settings at the followig link https://www.google.com/settings/security/lesssecureapps[^] and enable less secure apps . So that you will be able to login from all apps.