Technical : How to test Office 365 SMTP server using Powershell

Step 1: Run Powershell

Step 2: Enter your Office 365 User Details

$msolcred = get-credential

Step 3: Send Mail

Send-MailMessage –From user@domain.com –To user@hotmail.com –Subject “Test Email” –Body “Test SMTP Relay Service” -SmtpServer smtp.office365.com -Credential $msolcred -UseSsl -Port 587

Don't forget to replace the required information with your info.

eg: From, To, Subject, Body

Also please note the From address must be the same email address associated with the provided user credentials.