Looking for SMS, email, fax Notification library

[Yash Ganthe]

We are developing an ASP .NET application which needs to send
notifications to users through channels like SMS/email/fax, etc.
depending on the preference of the receiving user. We are looking for
a library that has methods for sending the notifications
asynchronously so that the calling program does not wait until the
message is sent. We may need the capability to also automatically
retry after a configured interval if an attempt to send fails.

Is there an existing library available in .NET to do this?

Thanks,
Yash