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SmtpClient API documentation for 21.5

We are running into an issue with the Message ID header being set incorrectly in version 18.6 and so are looking to upgrade to the latest Aspose.Email library, which appears to be 21.5. It appears, however, that APIs have changed and we are not seeing clear documentation about how the new API structure is supposed to be used. Specifically, BeginSend/EndSend no longer exist in 21.5. There is a SendAsync, but there isn’t a clear way to use a CancellationToken with this method. The ConnectionTimeout property also no longer appears to be available and it isn’t clear what the appropriate substitute is supposed to be.

Note that the API documentation on the Web site ( still references version 21.3 and talks about BeginSend/EndSend, but those methods don’t appear to exist in 21.5. Similarly, I found a .chm file in the Help subdirectory of my NuGet package install that seems to reference version 21.1. I also looked in the release notes and can’t find any indication of such breaking changes to the API. Where should we expect to find documentation of breaking changes of this kind?

Welcome to our community! Thank you for the query. I will answer you later as soon as possible.


I added a ticket with ID EMAILNET-40256 to our tracking system. Our development team will prepare information for you. I will inform you of any news.

Thank you for the comment. This API reference will be updated later.

You are right. Information about these changes and the new API should be in Release Notes 21.1. We apologize for any inconvenience caused.

The BeginSend and EndSend methods were deprecated in February 2019. And then they were removed from the API for net4.5 and netstandard in January 2020, as there is async/await. These methods are still relevant for versions net2.0, net3.5, net4.0.

I’m not sure that I understand. I looked through your release notes from 2019 and early 2020 and don’t see any mention of deprecation or removal of those APIs. Can you point me to documentation of the deprecation and removal? Does Aspose have a stated policy regarding the timeline and communication of API changes and removals? It is suprising that all of the documentation that I can find still references the BeginSend/EndSend pattern more than 2 years after you indicate that the API was deprecated.

We are also interested to know how to handle what was formerly the ConnectionTimeout property.

Do you have an estimated timeline for providing updated documentation?

As I mentioned above, this information wasn’t published. It is our mistake.

I will inform you when our development team prepares the information.

I requested an estimated time to fix the documentation. I will let you know as soon as possible.