Double ehlo appears to be preventing Mailsend.exe from working

[MatthewALHardy]

Hi,

I have a client using Office 365 hosted exchange. When testing manually from putty I note that each time I connect, the first time I issue either a helo or ehlo command. I received "500 5.3.3 Unrecognized command '????'" but then if I issue exactly the same command again I receive the expected response. I believe that this is an anti spam measure.
When I test from mailsend1.20b.exe the command fails.
Does anyone know if it's possible to tell mailsend to retry the ehlo command if it fails the first time?

Command and response as below

mailsend1.20b.exe -to me@mydomain.com -from sender@clientdomain.com -domain clientdomain.com -smtp clientdomain-com.mail.protection.outlook.com -sub "Subject LIne" +cc +bc -v < d:\path\file.LOG
Connecting to clientdomain-com.mail.protection.outlook.com:25
Will detect IPv4 or IPv6 automatically

libmsock: using getaddrinfo
AF_INET IPv4
IP address: xx.xx.xx.xx:xx
EINPROGRESS=10036,EWOULDBLOCK=10035
connect(): socket=332,rc=-1, errno=10035
Try socket 332
Setting read timeout to: 5 seconds
Windows Setting read timeout to: 5 seconds
[S] 220 CY1NAM02FT061.mail.protection.outlook.com Microsoft ESMTP MAIL Service r
eady at Fri, 11 Oct 2019 16:40:13 +0000
[C] EHLO clientdomain.com
Setting read timeout to: 5 seconds
Windows Setting read timeout to: 5 seconds
Winsock error[10060]: A connection attempt failed because the connected party di
d not properly respond after a period of time, or established connection failed
because connected host has failed to respond.

Error: Connection is closed unexpectedly
Error: EHLO failed
[C] MAIL FROM: sender@clientdomain.com

Setting read timeout to: 5 seconds
Windows Setting read timeout to: 5 seconds
Winsock error[10060]: A connection attempt failed because the connected party di
d not properly respond after a period of time, or established connection failed
because connected host has failed to respond.

Error: Connection is closed unexpectedly
Error: MAIL FROM failed: '-1 '
Could not send mail