$ss = new-object Security.SecureString
foreach ($ch in "password".ToCharArray())
{
    $ss.AppendChar($ch)
}
$cred = new-object Management.Automation.PSCredential "uid@domain.com", $ss
Send-MailMessage    -SmtpServer smtp.gmail.com -UseSsl -Credential $cred -Body...
	
Send-MailMessage : The SMTP server requires a secure connection or the client was not authenticated. The server response was: 5.5.1 Authentication Required. Learn
 more at                              
At foo.ps1:18 char:21
+     Send-MailMessage <<<<      `
    + CategoryInfo          : InvalidOperation: (System.Net.Mail.SmtpClient:SmtpClient) [Send-MailMessage], SmtpException
    + FullyQualifiedErrorId : SmtpException,Microsoft.PowerShell.Commands.SendMailMessage
	
$EmailFrom = "notifications@somedomain.com"
$EmailTo = "me@earth.com" 
$Subject = "Notification from XYZ" 
$Body = "this is a notification from XYZ Notifications.." 
$SMTPServer = "smtp.gmail.com" 
$SMTPClient = New-Object Net.Mail.SmtpClient($SmtpServer, 587) 
$SMTPClient.EnableSsl = $true 
$SMTPClient.Credentials = New-Object System.Net.NetworkCredential("username", "password"); 
$SMTPClient.Send($EmailFrom, $EmailTo, $Subject, $Body)
	
$smtpClient = new-object system.net.mail.smtpClient 
$smtpClient.Host = 'smtp.gmail.com'
$smtpClient.Port = 587
$smtpClient.EnableSsl = $true
$smtpClient.Credentials = [Net.NetworkCredential](Get-Credential GmailUserID) 
$smtpClient.Send('GmailUserID@gmail.com','yourself@somewhere.com','test subject', 'test message')
	
# append to Christian's code above --^
$emailMessage = New-Object System.Net.Mail.MailMessage
$emailMessage.From = $EmailFrom
$emailMessage.To.Add($EmailTo)
$emailMessage.Subject = $Subject
$emailMessage.Body = $Body
$emailMessage.Attachments.Add("C:Test.txt")
$SMTPClient.Send($emailMessage)
	
## Send-Gmail.ps1 - Send a gmail message
## By Rodney Fisk - xizdaqrian@gmail.com
## 2 / 13 / 2011

# Get command line arguments to fill in the fields
# Must be the first statement in the script
param(
    [Parameter(Mandatory = $true,
                    Position = 0,
                    ValueFromPipelineByPropertyName = $true)]
    [Alias('From')] # This is the name of the parameter e.g. -From user@mail.com
    [String]$EmailFrom, # This is the value [Don't forget the comma at the end!]

    [Parameter(Mandatory = $true,
                    Position = 1,
                    ValueFromPipelineByPropertyName = $true)]
    [Alias('To')]
    [String[]]$Arry_EmailTo,

    [Parameter(Mandatory = $true,
                    Position = 2,
                    ValueFromPipelineByPropertyName = $true)]
    [Alias( 'Subj' )]
    [String]$EmailSubj,

    [Parameter(Mandatory = $true,
                    Position = 3,
                    ValueFromPipelineByPropertyName = $true)]
    [Alias( 'Body' )]
    [String]$EmailBody,

    [Parameter(Mandatory = $false,
                    Position = 4,
                    ValueFromPipelineByPropertyName = $true)]
    [Alias( 'Attachment' )]
    [String[]]$Arry_EmailAttachments

)

# From Christian @ StackOverflow.com
$SMTPServer = "smtp.gmail.com" 
$SMTPClient = New-Object Net.Mail.SMTPClient( $SmtpServer, 587 )  
$SMTPClient.EnableSSL = $true 
$SMTPClient.Credentials = New-Object System.Net.NetworkCredential( "GMAIL_USERNAME", "GMAIL_PASSWORD" ); 

# From Core @ StackOverflow.com
$emailMessage = New-Object System.Net.Mail.MailMessage
$emailMessage.From = $EmailFrom
foreach ( $recipient in $Arry_EmailTo )
{
    $emailMessage.To.Add( $recipient )
}
$emailMessage.Subject = $EmailSubj
$emailMessage.Body = $EmailBody
# Do we have any attachments?
# If yes, then add them, if not, do nothing
if ( $Arry_EmailAttachments.Count -ne $NULL ) 
{
    $emailMessage.Attachments.Add()
}
$SMTPClient.Send( $emailMessage )
	
$smtpmail = [System.Net.Mail.SMTPClient]("127.0.0.1")
$smtpmail.Send("myacct@gmail.com", "myacct@gmail.com", "Test Message", "Message via local smtp")
	
$filename = “c:scripts_scotttest9999.xls”
$smtpserver = “smtp.gmail.com”
$msg = new-object Net.Mail.MailMessage
$att = new-object Net.Mail.Attachment($filename)
$smtp = new-object Net.Mail.SmtpClient($smtpServer )
$smtp.EnableSsl = $True
$smtp.Credentials = New-Object System.Net.NetworkCredential(“username”, “password_here”); # Put username without the @GMAIL.com or – @gmail.com
$msg.From = “username@gmail.com”
$msg.To.Add(”boss@job.com”)
$msg.Subject = “Monthly Report”
$msg.Body = “Good MorningATTACHED”
$msg.Attachments.Add($att)
$smtp.Send($msg)