如何在 asp.net MVC 中验证 smtp 主机？

Question

I want to validate SMTP host and port. Please let me know how can I do this? I want to smtp.gmail.com or smtp-mail.outlook.com. But now my code is allowing numbers also.

public int Smtp_Id{ get; set; }

[Display(Name="Mail From")]
[Required(ErrorMessage = "Please enter senders mail address.")]
[EmailAddress(ErrorMessage = "Invalid Email Address")]
public string Smtp_mailfrom { get; set; }

[Display(Name = "SMTP Host")]
[Required(ErrorMessage = "Please enter host name.")]     
public string Smtp_Host { get; set; }

[Display(Name = "User Name")]
[Required(ErrorMessage = "Please enter username.")]
[MaxLength(50,ErrorMessage="Username Should not be more than 50 charachters.")]
public string Smtp_username { get; set; }

[Display(Name = "Password")]
[MaxLength(50, ErrorMessage = "Password Should not be more than 50 charachters.")]
[Required(ErrorMessage = "Please enter password.")]
public string Smtp_password { get; set; }

[Display(Name = "SMTP Port")]
[Required(ErrorMessage = "Please enter Port.")]
public int Smtp_Port { get; set; }

Answer 1

For host name you need to regular expression and for the port no you need something custom like as below it will helpful to you.

    [Display(Name = "SMTP Host")]
    [Required(ErrorMessage = "Please enter host name.")]
    [RegularExpression("smtp.gmail.com|smtp-mail.outlook.com")]
    public string Smtp_Host { get; set; }


    [Display(Name = "SMTP Port")]
    [Required(ErrorMessage = "Please enter Port.")]
    [RegularExpression("([1-9][0-9]*)", ErrorMessage = "Count must be a natural number")]
    [Range(1, 9999, ErrorMessage = "Port no must between 1 to 9999")]     
    public int Smtp_Port { get; set; }