"Connection Rejected"
if I remember correctly Office 365 requires oAuth 2.0 authentication and the port can't be 25 (maybe 465 or 587), TLS 1.2
You could try to send mail with normal CDO with the same parameters (port 25, w/o authentication) just to see if it is possible or what error message this will return.

This works for me (I don't receive any eMail though)

SendCDOMail()


FUNCTION SendCDOMail()
SET STEP ON 
    LOCAL loCDOMesage AS CDO.Message
    LOCAL loCDOConfig AS CDO.Configuration

    lcSchema    = [http://schemas.microsoft.com/cdo/configuration/]
    loCDOConfig = CREATEOBJECT([CDO.Configuration])
    WITH loCDOConfig.FIELDS
         .ITEM(lcSchema + [smtpserverport])   = 25
         .ITEM(lcSchema + [sendusing])        = 2
         .ITEM(lcSchema + [smtpserver])       = "smtp.freesmtpservers.com"
         .ITEM(lcSchema + [smtpauthenticate]) = 0
         .ITEM(lcSchema + [sendusername])     = ""
         .ITEM(lcSchema + [sendpassword])     = ""
         .ITEM(lcSchema + [smtpusessl])       = .f.
         .UPDATE()
    ENDWITH
    loCDOMesage = CREATEOBJECT([CDO.Message])
    loCDOMesage.Configuration = m.loCDOConfig
    loCDOMesage.BodyPart.Charset     = "utf-8"

    WITH loCDOMesage
         .From     = "from@somemail.com"
         .To       = "to@somemail.com"
         .Subject  = "This is a test"
         .HTMLBody = "Test of the body contets"
         .HTMLBodyPart.Charset = "utf-8"
         .TextBodyPart.Charset = "utf-8"
         TRY
            .Send()
         CATCH TO oError
            MesageBox(oError.Message)
         ENDTRY
    ENDWITH

    loCDOMesage = NULL
    loCDOConfig = NULL
    RELEASE loCDOConfig, loCDOMesage
RETURN ""

***** UPDATE
Maybe Chilkat smtpauthenticate equivalent is TRUE by default?
Maybe if you change it to FALSE it will work?


>I'm just getting started replacing an old email module I wrote for a client that doesn't seem to be working for their customers anymore.
>
>For various reasons, choosing to do this with Chilkat and the new ChilkatVFP wrapper. I've figured out the code I need to create and send an email, but I'm struggling in testing it. When I tried to configure it to use the SMTP server associated with my Office365-based Exchange Server, I got authentication errors.
>
>I poked around and found a cool site that provides a test SMTP server online so you can test email issues (https://www.wpoven.com/tools/free-smtp-server-for-testing). Even found a different site that lets you test sending via SMTP (https://smtpserver.com/smtptest). When I use the second site to send an email using the first site's server, the email goes through without error, so I know I've got the right SMTP settings.
>
>But when I use my code to try to send via the first site, I time out. This is really simple code, just to make sure I can make it all work. After the necessary SET PATH and SET CLASSLIB, it's just:
>
>

>loEmail = CREATEOBJECT('Email')
>loEmail.Subject = 'This is a test'
>loEmail.Body = [Here's some content.]
>loEmail.From = 'tamar@istesting.com'
>?loEmail.AddTo('tamar@didthiswork.com')
>
>loMailMan = CREATEOBJECT('MailMan')
>loMailman.smtphost = 'smtp.freesmtpservers.com'
>loMailman.smtpport = 25
>?loMailman.Sendemail(loEmail)
>_cliptext = loMailMan.lasterrortext
>

>
>The error message I get is:
>
>

>ChilkatLog:
>  SendEmail:
>    DllDate: Oct 27 2023
>    ChilkatVersion: 9.5.0.96
>    UnlockStatus: 0
>    Architecture: Little Endian; 32-bit
>    Language: ActiveX
>    VerboseLogging: 0
>    Auto unlock for 30-day trial
>    UnlockStatusMsg: Unlocked for 30-day trial
>    UnlockStatus: 1
>    sendEmailInner:
>      ReadTimeout: 30000
>      renderToMime_pt1:
>        createEmailForSending:
>          Auto-generating Message-ID
>        --createEmailForSending
>      --renderToMime_pt1
>      sendMimeInner:
>        ensureSmtpSession:
>          ensureSmtpConnection:
>            smtpParams:
>              SmtpHost: smtp.freesmtpservers.com
>              SmtpPort: 25
>              SmtpUsername: 
>              SmtpSsl: 0
>              StartTLS: 0
>            --smtpParams
>            smtpConnect:
>              smtpHostname: smtp.freesmtpservers.com
>              smtpPort: 25
>              connectionIsReady:
>                SMTP host changed.
>                Need new SMTP connection...
>              --connectionIsReady
>              smtpSocketConnect:
>                socket2Connect:
>                  connect2:
>                    connectSocket_v2:
>                      connect_domain:
>                        Connection attempt failed.
>                        maxWaitTimeMs: 30000
>                        totalMsWaitedSoFar: 17550
>                        Failed.
>                      --connect_domain
>                    --connectSocket_v2
>                    ConnectFailReason: Connection rejected
>                    A few possible causes for a connection being rejected are:
>                    - A firewall (software or hardware), such as Windows Firewall, is blocking the connection .
>                    - Nothing is listening at the remote host:port
>                  --connect2
>                --socket2Connect
>                Failed to connect to SMTP server..
>              --smtpSocketConnect
>            --smtpConnect
>          --ensureSmtpConnection
>        --ensureSmtpSession
>      --sendMimeInner
>    --sendEmailInner
>    Failed.
>  --SendEmail
>--ChilkatLog
>

>
>Any suggestions about what I'm missing here?
>
>Tamar