– Failed to get initial SMTP Response

If something on the client-side is blocking communications, such as a hardware or software firewall, or anti-virus, then it may be that a TLS connection is established, but then trying to read the 1st message from the server gets blocked.  When this happens, the contents of the LastErrorText look like this.   (The LastErrorText for a successful connection is shown below.) […]

Auto-Reconnect Feature of Chilkat.Rest Explained

This post is to explain the auto-reconnect argument in the Chilkat.Rest.Connect method.  For example, the Rest.Connect method in C#. The Chilkat REST class is designed so that your application initially connects to a particular web server (at a particular port, with or without TLS), and then one or more requests can be sent. If the auto-connect argument was set to […]

Convert to Chilkat PrivateKey, to Chilkat Certificate

Question: We are facing some problems about private key and x509 cert. In our case, we already have instance of and How can we convert these instance to CkPrivateKey and CkCert for using in CkXmlDSignGen? Private Key Answer: Google Go to reference doc page: Find way to get the private key in some format.  (Chilkat can […]

Error: “No Content-Length header AND not a chunked response. Assuming no response body.”

The following error was received from a call to Rest.FullRequestSb: ChilkatLog: FullRequestSb: DllDate: Mar 23 2022 ChilkatVersion: Architecture: Little Endian; 64-bit VerboseLogging: 0 uriPath: … fullRequestBody: autoReconnect: 1 Sending request with body… sendReqBody: … –sendReqBody Sent request. fullRequestGetResponse: Reading response header… responseStatusCode: 200 Reading response body … readResponseBody: No Content-Length header AND not a chunked response. Assuming no response […]

undefined reference to `__res_query’

Question: Trying to link Chilkat (C++) with the following libs: LIBS=-lstdc++fs \ -pthread \ -L${FMT_LIB} -lfmt \ -lspdlog \ /usr/local/lib/libredis++.a \ ${BOOST_LIB}/libboost_json.a \ … … ${CHILKAT_LIB}/libchilkat-9.5.0.a \ -lmongoc-1.0 -lbson-1.0 \ -lpthread \ -ldl \ -lresolv After we went from ubuntu 21 to 22 LTS, using same compiler, it stopped working. Now we get errors: /usr/bin/ld: … libchilkat-9.5.0.a(ChilkatResolve.o): in function `ChilkatResolve::bestMxLookup(char […]

SMTP / Office 365 / OAuth2 : SmtpCmdResp: 535 5.7.3 Authentication unsuccessful

Question: A customer wants to send emails with Office 365 and OAuth2 Authentication. The setup of the application in Azure is OK. It works for one user. For another user we have the following error: SmtpCmdResp: 535 5.7.3 Authentication unsuccessful [****.****] For authentication I use the example: What is surprising is that for the second user on same PC, […]

Install PHP Extensions on Shared Hosting (such as BlueHost)?

Question: Is it possible to install the Chilkat PHP extension at a sharing host like Bluehost?  I’ve been trying but no success until now, so I am starting to think that it isn’t possible. Answer:  It doesn’t look like it’s possible: You might consider hosting on Amazon EC2.  It can be quite inexpensive, you’ll have full control over your […]

GMail SMTP with Send-Only Scope? (

Apparently the full permission scope is required to do XOAUTH2 authentication in the SMTP protocol for GMail. See these examples The full permission scope is “” The send-only scope is: “” Google claims that it’s possible to send email with the send-only scope, but we’ve found it is  simply possible.  It just doesn’t work. Don’t know why. Perhaps […]

AWS Presigned URLs for Services Other than S3?

There is a big unsolved mystery:  Is it possible to create pre-signed URLs for AWS services other than S3?    For example, is it possible to create a pre-signed URL that allows the user to send an SES email? We simply don’t know.  Theoretically it seems it should be possible.  However, all AWS pre-signed URL documentation or examples has to do […]

Chilkat 4-May-2022 – This Python version does not match the downloaded Chilkat module.

Question: Unable to install Chilkat because of the Python version and architecture error: “This Python version does not match the downloaded Chilkat module.” Answer: Refer to the install instructions here: You can open the script in a text editor to see what it does.  It’s simply verifying that your version of Python (such as “3.7”) matches the version […]