public bool Contains(
	Certificate cert
)

Public Function Contains ( 
	cert As Certificate
) As Boolean

// To use the code below, import MailBee namespace at the top of your code
using MailBee.Security;

// The actual code (put it into a method of your class)
Certificate cert = new Certificate(@"C:\Temp\certificate.cer", CertFileType.Cer, null);
CertificateStore store = new CertificateStore(@"C:\Temp\my_store.p7b", CertStoreType.PublicFile, null);
CertificateCollection collection = store.GetAllCertificates();

// Add certificate to the collection if it doesn't contain such certificate
if (!collection.Contains(cert))
{
    store.AddCertificate(cert, false);
}
store.SaveToFile(@"C:\Temp\my_store.p7b", CertStoreFileType.P7b, null);

' To use the code below, import MailBee namespace at the top of your code
Imports MailBee.Security

' The actual code (put it into a method of your class)
Dim cert As Certificate = New Certificate("C:\Temp\certificate.cer", CertFileType.Cer, Nothing)
Dim store As CertificateStore = New CertificateStore("C:\Temp\my_store.p7b", CertStoreType.PublicFile, Nothing)
Dim Collection As CertificateCollection = store.GetAllCertificates()

' Add certificate to the collection if it doesn't contain such certificate
If Not Collection.Contains(cert) Then
    store.AddCertificate(cert, False)
End If

store.SaveToFile("C:\Temp\my_store.p7b", CertStoreFileType.P7b, Nothing)