public void AddRecipientMetadata(string rcptEmail, string key, string value)
        {
            var metadata = RecipientMetadata.FirstOrDefault(x => x.Rcpt == rcptEmail);

            if (metadata == null)
            {
                RecipientMetadata.Add(metadata = new MandrillRcptMetadata {
                    Rcpt = rcptEmail
                });
            }
            metadata.Values[key] = value;
        }
 public void AddRecipientMetadata(string rcptEmail, string key, string value)
 {
     var metadata = RecipientMetadata.FirstOrDefault(x => x.Rcpt == rcptEmail);
     if (metadata == null)
     {
         RecipientMetadata.Add(metadata = new MandrillRcptMetadata {Rcpt = rcptEmail});
     }
     metadata.Values[key] = value;
 }