Please refer to the steps below to send Email via Port 587 with openssl
Telnet cannot be used as once you issues STARTTLS, the session will be encrypted and you will not be able to enter any commands
Port 587 – Securing SMTP communications using Transport Layer Security (TLS). STARTTLS
Prepare your username & password with PowerShell
#Convert your username to BASE64
$Username = [System.Text.Encoding]::UTF8.GetBytes("[email protected]")
[System.Convert]::ToBase64String($Username)
#Convert your Password to BASE64
$Password = [System.Text.Encoding]::UTF8.GetBytes("P@ssw0rd")
[System.Convert]::ToBase64String($Password)
#Decode BASE64 back to normal text
$DecodeBase64 = [System.Convert]::FromBase64String("bTN0ZXN0QGJlbmFsZWMuY29tLm15")
[System.Text.Encoding]::UTF8.GetString($DecodeBase64)
Open MobaXterm and enter the following commands
you can install openssl with “apt-get install openssl” if you have not done so
#Connect to port 587 with Starttls
openssl s_client -starttls smtp -crlf -connect 10.3.3.23:587
#Enter helo / ehlo
helo
#Login using Username & Password (BASE64 Format)
auth login
334 VXNlcm5hbWU6
XXXXXXXXXXXXXXXXXXX #Username (BASE64) here
334 UGFzc3dvcmQ6
XXXXXXXXXXXXXXXX #Password (BASE64) here
235 2.7.0 Authentication successful
#Standard SMTP Telnet commands here
mail from:<[email protected]>
250 2.1.0 Sender OK
rcpt to:<[email protected]>
250 2.1.5 Recipient OK
data
354 Start mail input; end with <CRLF>.<CRLF>
subject: My Test Email
helo,
Testing Email
. #put . here to stop and start to deliver the email
250 2.6.0 <[email protected]> [InternalId=72026601553977, Hostname=mail.test.com] Queued mail for delivery