How to validate smtp credentials before sending mail?

by

There is no way.

SmtpClient bascially can not validate the usernamepassword without contacting the serve it connects to.

What you could do is do it outside SmtpClient, by opening a TCP connection to the server… but authentication CAN be complicated depending how the server is configured.

May I ask WHY you need to know that before sending? normal behavior IMHO would be to wrap sending in appropriate error handling to catch exceptions here.

More Related Contents:

  1. How to read embedded resource text file
  2. What is the difference between IQueryable and IEnumerable?
  3. Could you explain STA and MTA?
  4. Open Source Alternatives to Reflector? [closed]
  5. Disable SSL fallback and use only TLS for outbound connections in .NET? (Poodle mitigation)
  6. Logging, Aspect Oriented Programming, and Dependency Injection – Trying to make sense of it all
  7. Calculate week of month in .NET
  8. How do I get the MAX row with a GROUP BY in LINQ query?
  9. Custom titlebars/chrome in a WinForms app
  10. Is Mono ready for prime time? [closed]
  11. Parameterized Queries with LIKE and IN conditions
  12. Form_Load() ‘event’ or Override OnLoad()
  13. How do I set a number of retry attempts in RabbitMQ?
  14. How to use System.Windows.Forms in .NET Core class library
  15. Referencing Google’s V8 engine from a .NET app
  16. Does LINQ work with IEnumerable?
  17. How to improve painting performance of DataGridView?
  18. How to get Windows native look for the .NET TreeView?
  19. How are .NET 4 GUIDs generated?
  20. How to use Observable.FromEvent instead of FromEventPattern and avoid string literal event names
  21. System.IO.FileSystemWatcher to monitor a network-server folder – Performance considerations
  22. Windows SDK 7.1 Setup failure
  23. How do you databind to a System.Windows.Forms.Treeview control?
  24. Get a list of groups that Azure AD user belongs to in claims
  25. What version of .NET ships with what version of Windows?
  26. Get Current .NET CLR version at runtime?
  27. How to determine ACTUAL windows form size (with all nonclient elements) when running Aero?
  28. InvalidOperationException: Unable to resolve service for type ‘Microsoft.AspNetCore.Http.IHttpContextAccessor’
  29. Integrate existing ASP.NET MVC application with Orchard CMS
  30. Serializing a list of Key/Value pairs to XML

Leave a Comment