I'm having similar issue with 9.1 VM Pro's but not 11.0.
These are ones using Microsoft.
Looks like not able to do handshake. Assuming a TLS issue.
27/10/2021 14:37:06.997 - Attempting to connect to host smtp.office365.com on port 587, local bound address is (null)
27/10/2021 14:37:07.088 - Successfully connected to host smtp.office365.com on port 587
27/10/2021 14:37:07.139 - < 220 CH0PR03CA0357.outlook.office365.com Microsoft ESMTP MAIL Service ready at Wed, 27 Oct 2021 19:37:07 +0000
27/10/2021 14:37:07.189 - ######## START OF CHUNK ######
27/10/2021 14:37:07.241 - > EHLO FAKE-VMPRO
27/10/2021 14:37:07.317 - ######## END OF CHUNK ######
27/10/2021 14:37:07.399 - < 250-CH0PR03CA0357.outlook.office365.com Hello [12.231.201.3]
27/10/2021 14:37:07.399 - 250-SIZE 157286400
27/10/2021 14:37:07.399 - 250-PIPELINING
27/10/2021 14:37:07.399 - 250-DSN
27/10/2021 14:37:07.399 - 250-ENHANCEDSTATUSCODES
27/10/2021 14:37:07.399 - 250-STARTTLS
27/10/2021 14:37:07.399 - 250-8BITMIME
27/10/2021 14:37:07.399 - 250-BINARYMIME
27/10/2021 14:37:07.399 - 250-CHUNKING
27/10/2021 14:37:07.399 - 250 SMTPUTF8
27/10/2021 14:37:07.471 - ######## START OF CHUNK ######
27/10/2021 14:37:07.533 - > STARTTLS
27/10/2021 14:37:07.596 - ######## END OF CHUNK ######
27/10/2021 14:37:07.633 - < 220 2.0.0 SMTP server ready
27/10/2021 14:37:07.712 - ######## START OF CHUNK ######
27/10/2021 14:37:07.750 - > EHLO FAKE-VMPRO
27/10/2021 14:37:07.813 - CSMTPConnection::SendChunk: Failed to send data chunk error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure
27/10/2021 14:37:07.875 - CSMTPConnection::ConnectESMTP: An unexpected error occurred while sending the EHLO command. error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure
27/10/2021 14:37:07.912 - ######## START OF CHUNK ######
27/10/2021 14:37:07.950 - > HELO FAKE-VMPRO
27/10/2021 14:37:08.012 - CSMTPConnection::SendChunk: Failed to send data chunk error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure
27/10/2021 14:37:08.076 - CSMTPConnection::ConnectSMTP: An unexpected error occurred while sending the HELO command error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure
27/10/2021 14:37:08.113 - ######## START OF CHUNK ######
27/10/2021 14:37:08.176 - > QUIT
27/10/2021 14:37:08.212 - CSMTPConnection::SendChunk: Failed to send data chunk error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure
27/10/2021 14:37:08.276 - CSMTPConnection:

isconnect: Failed in call to send QUIT command error:140790E5:SSL routines:SSL23_WRITE:ssl handshake failure
27/10/2021 14:37:08.313 - <
27/10/2021 14:37:08.375 - CSMTPConnection:

isconnect: An unexpected QUIT response was received
27/10/2021 14:37:08.437 - CSMTPConnection::Connect: An unexpected HELO/EHLO response was received
27/10/2021 14:37:08.525 - CSMTPConnection:

isconnect: Already disconnected from SMTP server, doing nothing