Basic Authentication
PORT = 587
Use SSL = True
Server Name = smtp.office365.com

TLS 1.2 is required.

How to set up a multifunction device or application to send email using Microsoft 365 or Office 365 also says:

Transport Layer Security (TLS): Your device must be able to use TLS version 1.2 and above.

• DatabaseMail.exe is built for .NET Framework 3.5, but you need a .NET Framework installed that supports TLS 1.2 (.NET Framework 4.5.2 or later).
• TLS 1.2 client protocol should be enabled at the machine level in Registry

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\SecurityProviders\SCHANNEL\Protocols\TLS 1.2\Client]
"DisabledByDefault"=dword:00000000
"Enabled"=dword:00000001

• TLS 1.2 client protocol should be enabled for .NET Framework 4.x in the Registry

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\.NETFramework\v4.0.30319]
"SchUseStrongCrypto"=dword:00000001

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\.NETFramework\v4.0.30319]
"SchUseStrongCrypto"=dword:00000001

• An appropriate supportedRuntime should be in DatabaseMail.exe.config file, e.g.: with Microsoft .NET Framework 4.5.2 installed:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <appSettings>
    <add key="DatabaseServerName" value="." />
    <add key="DatabaseName" value="msdb" />
  </appSettings>
  <startup> 
    <supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.2" />
  </startup>
</configuration>

3. Via the Database Mail settings in SSMS, configure the sending account appropriately:

• Server name: smtp.office365.com
• Port number: 587 (preferred, or 25)
• This server requires a secure connection (SSL): must be ticked (this enables STARTTLS)
• SMTP Authentication:
  • Basic authentication (selected)
    • User name: sending_mailbox_user@your_domain.com
    • Password: your_office365_password
    • Confirm password: your_office365_password_again