The case was auto-closed, but I have re-opened it. I do think a sample project of any kind would be helpful. If someone has something they can share, please add it to the case.
The key problem is the other end rejects the request because of the initial TLS 1.0 handshake. You have to connect to a server that rejects the initial TLS 1.0 request like Office 365. The SMTPSecureSocket.xojo_binary_project example project will do this.
Not all Office365 shows that behavior, not sure why. I have right now one account that does and the other not. Same server, same settings but different credentials.
This is the one that connects:
[01] 4/14 11:07:00 220 BN6PR11CA0069.outlook.office365.com Microsoft ESMTP MAIL Service ready at Thu, 14 Apr 2022 17:06:59 +0000
[01] 4/14 11:07:00 > EHLO [192.168.100.82]
[01] 4/14 11:07:00 250-BN6PR11CA0069.outlook.office365.com Hello [179.42.225.0]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
[01] 4/14 11:07:00 > STARTTLS
[01] 4/14 11:07:00 220 2.0.0 SMTP server ready
[01] 4/14 11:07:00 ~ Connected
[01] 4/14 11:07:00 > EHLO [192.168.100.82]
[01] 4/14 11:07:00 250-BN6PR11CA0069.outlook.office365.com Hello [179.42.225.0]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-AUTH LOGIN XOAUTH2
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
[01] 4/14 11:07:00 > AUTH LOGIN
[01] 4/14 11:07:00 334 VXNlcm5hbWU6
[01] 4/14 11:07:00 > maxprog@hotmail.com
[01] 4/14 11:07:00 334 UGFzc3dvcmQ6
[01] 4/14 11:07:00 > ********************
[01] 4/14 11:07:03 235 2.7.0 Authentication successful
and the one that doesn’t:
[01] 4/14 11:09:33 220 BN6PR1401CA0006.outlook.office365.com Microsoft ESMTP MAIL Service ready at Thu, 14 Apr 2022 17:09:32 +0000
[01] 4/14 11:09:33 > EHLO [192.168.100.82]
[01] 4/14 11:09:33 250-BN6PR1401CA0006.outlook.office365.com Hello [179.42.225.0]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-STARTTLS
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
[01] 4/14 11:09:33 > STARTTLS
[01] 4/14 11:09:33 220 2.0.0 SMTP server ready
[01] 4/14 11:09:33 ~ Connected
[01] 4/14 11:09:33 > EHLO [192.168.100.82]
[01] 4/14 11:09:33 250-BN6PR1401CA0006.outlook.office365.com Hello [179.42.225.0]
250-SIZE 157286400
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-AUTH LOGIN XOAUTH2
250-8BITMIME
250-BINARYMIME
250-CHUNKING
250 SMTPUTF8
[01] 4/14 11:09:33 > AUTH LOGIN
[01] 4/14 11:09:33 334 VXNlcm5hbWU6
[01] 4/14 11:09:33 > Maxbulk@totalfood.com
[01] 4/14 11:09:33 334 UGFzc3dvcmQ6
[01] 4/14 11:09:33 > ********
[01] 4/14 11:09:34 421 4.7.66 TLS 1.0 and 1.1 are not supported. Please upgrade/update your client to support TLS 1.2. Visit New opt-in endpoint available for SMTP AUTH clients still needing legacy TLS - Microsoft Tech Community. [BN6PR1401CA0006.namprd14.prod.outlook.com]
Because Microsoft rejects this only at a certain percentage which is increased every month until only >=TLS 1.2 is accepted.
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