I cant send Newsletters from my site nor send contents of contact and feedback forms to their recipients. For the newsletter, I get this error message. Any help please?

Error: Newsletters is currently unavailable. DotNetNuke.Services.Exceptions.ModuleLoadException: The input data is not a complete block. ---> System.Security.Cryptography.CryptographicException: The input data is not a complete block. at System.Security.Cryptography.CapiSymmetricAlgorithm.TransformFinalBlock(Byte[] inputBuffer, Int32 inputOffset, Int32 inputCount) at System.Security.Cryptography.CryptoStream.Read(Byte[] buffer, Int32 offset, Int32 count) at DotNetNuke.Security.FIPSCompliant.DecryptAES(String encryptedText, String passPhrase, String salt, Int32 iterations) at 

DotNetNuke.Entities.Host.Host.get_SMTPPassword() at DotNetNuke.Modules.Admin.Newsletters.Newsletter.SendMailAsyncronously(SendTokenizedBulkEmail email, String& message, ModuleMessageType& messageType) at DotNetNuke.Modules.Admin.Newsletters.Newsletter.SendEmail(List`1 roleNames, List`1 users, String& message, ModuleMessageType& messageType) at DotNetNuke.Modules.Admin.Newsletters.Newsletter.OnSendClick(Object sender, EventArgs e) --- End of inner exception stack trace ---