$PSEmailServer vs $smtpServer

Hi,
Requirement:
Powershell script run SSRS report and get response as pdf in Powershell script and email it as attachment. This powershell script gets called in sql job step. Not working. So, want to troubleshoot the script locally to make sure it is working.

**Try 1: ** NOT WORKING

   This is done as:   
          param(  
                  [string]$pRunDate  
              )  
   $pRunDate = Get-Date -Format "yyyy-MM-dd"  
   $url = "http://server/ReportServer?/TT/TR%20Pl%20UU%20GL%20TradeDate&pRunDate="  
   $uri = "$url$pRunDate&rs:Format=PDF"  
   $R = Invoke-WebRequest -Uri  $uri -UseDefaultCredentials   

2. Email $R stream
# Sender and Recipient Info
$MailFrom = "******@gmail.com"
$MailTo = "yy.gmail.com"

  # Server Info  
       $SmtpServer = "cxxx.xxxx"  
       #$SmtpPort = "25"   

  # Message stuff  
      $MessageSubject = "test"   
      $Message = New-Object System.Net.Mail.MailMessage $MailFrom,$MailTo  
      $Message.IsBodyHTML = $true  
      $Message.Subject = $MessageSubject  
      $Message.Body = 'Testing without content'  
  $stream = New-Object System.IO.MemoryStream -ArgumentList @(,$R.Content)  
    $attachment = New-Object Net.Mail.Attachment -ArgumentList @($stream, 'myreport.pdf')  

# Add the attachment  
$message.Attachments.Add($attachment)  

  # Construct the SMTP client object, credentials, and send  
  $Smtp = New-Object Net.Mail.SmtpClient($SmtpServer,$SmtpPort)  
  $Smtp.Send($Message)  

But this script run email doesn't work locally.

Try 2: DOESN'T WORK
So, I tested using send mail message
Send-MailMessage -From 'User01 <hh@Stuff .com>' -To 'User02 <yy@Stuff .com>' -Subject 'Test mail' -SmtpServer “<xxx.xx>”

Error: Send-MailMessage : The remote name could not be resolved: '<xxx.xx>'

Try 3: WORKS
$PSEmailServer = 'xxx.xx'

     Send-MailMessage -From '******@gmail.com' -To '******@gmail.com' -Subject 'Test mail'  

but I don't know how to attach memory stream object to Try 3 scenario

Any help or suggestion is appreciated.
I tried to google difference between $PSEmailServer Vs $SmtpServer