Sending E-mail to Multiple Recipients with Authentication - email

Question

I am trying to send an e-mail through Powershell. I can send e-mails to one recipient without a problem using the code below. However, when I add a second recipient to the $EmailTo variable, I do not get the e-mail. I do not get any errors either. I did some research and it appears that the SMTP Client way of sending e-mails does not take multiple recipients.
$EmailFrom = "sender#email.com"
$EmailTo = "recipient1#email.com"
$EmailBody = "Test Body"
$EmailSubject = "Test Subject"
$Username = "carlos#email.com"
$Password = "12345"
$Message = New-Object Net.Mail.MailMessage($EmailFrom, $EmailTo, $EmailSubject, $EmailBody)
$SMTPClient = New-Object Net.Mail.SmtpClient("smtp.com", 123) #Port can be changed
$SMTPClient.EnableSsl = $true
$SMTPClient.Credentials = New-Object System.Net.NetworkCredential($Username, $Password);
$SMTPClient.Send($Message)
I tried with the Send-MailMessage command but it is giving me issues.
Send-MailMessage -from $EmailFrom -to $EmailTo -Subject $EmailSubject `
-smtpserver smtp.com -usessl `
-credential (new-object System.NetworkCredential("$Username","$Password"))
The error I get with this is
Cannot find type [System.NetworkCredential]...
Any ideas on what the best way to send emails to multiple recipients with authentication would be?

Answer 1

Make sure you separate your $EmailTo address list with commas and don't pass as an array. i.e:
Do this:
$EmailTo = "recipient1#email.com,recipient2#email.com"
Don't do this:
$EmailTo = "recipient1#email.com","recipient2#email.com"
or this:
$EmailTo = "recipient1#email.com;recipient2#email.com"
That last one would throw the following exception which you'd easily notice:
New-Object : Exception calling ".ctor" with "4" argument(s): "The specified string is not in the form required for an e-mail address."

Answer 2

The class name is System.Net.NetworkCredential, not System.NetworkCredential.
Change this:
Send-MailMessage -from $EmailFrom -to $EmailTo -Subject $EmailSubject `
-smtpserver smtp.com -usessl `
-credential (new-object System.NetworkCredential("$Username","$Password"))
into this:
Send-MailMessage -From $EmailFrom -To $EmailTo -Subject $EmailSubject `
-SmtpServer smtp.com -UseSsl `
-Credential (New-Object Net.NetworkCredential($Username, $Password))
and the problem should disappear.