CheckCreate

$dcs = 'dc1.domain1.company.local','dc2.domain2.company.local'
$ErrorCount = 0
$DC2match = "^The operation couldn't be performed because object '.*' couldn't be found on 'dc1\.domain1\.company\.local'\.$"
$DC1match = "^The operation couldn't be performed because object '.*' couldn't be found on 'dc2\.domain2\.company\.local'\.$""
$firstname = Read-Host -Prompt 'Enter First Name'
$lastname = Read-Host -Prompt 'Enter Last Name'
$alias = $firstname.substring(0,1).tolower()+$lastname.tolower()
$primarysmtpaddress = $alias+'@company.com'

foreach ($dc in $dcs)
{

    try {
        $Mailbox = Get-Recipient -DomainController $dc -Identity $PrimarySmtpAddress -ErrorAction Stop

}   catch  {
        $MailboxError = $_.Exception.Message
        $MailboxErrorRegex = "^The operation couldn't be performed because object '.*' couldn't be found on '.*'\.$"

        if ($MailboxError -match $MailboxErrorRegex) {
            $ErrorCount++
            }
}
}

if ($ErrorCount -eq 2) {
    $pw = Read-Host -Prompt "Enter Password" -AsSecureString
    $db = Read-Host -Promp "Enter Database"
    $name = $firstname+' '+$lastname
    $upn = $alias+'@domain1.company.local'
    $x400 = 'X400:C=US;A= ;P=Company;O=OU;S='+$lastname+';G='+$firstname+';'
    $identity = 'domain1.company.local/OU/OU/'+$name
    $secondsmtpaddress = 'smtp:'+$alias+'@secondsmtpaddress.com'

    New-Mailbox -Name $name -Alias $alias -OrganizationalUnit 'domain1.company.local/OU/OU' -UserPrincipalName $upn -SamAccountName $alias -FirstName $firstname -Initials '' -LastName $lastname -Password $pw -ResetPasswordOnNextLogon $false -Database $db -PrimarySmtpAddress $primarysmtpaddress
}

    elseif ($Error[0].Exception.Message -match $DC2match) {
        Write-Host Exists on Domain2
    }

    elseif ($Error[0].Exception.Message -match $DC1match) {
        Write-Host Exists on Domain1
    }

if ($ErrorCount -eq 2) {
    Set-Mailbox -EmailAddressPolicyEnabled $false -EmailAddresses $primarysmtpaddress,$secondsmtpaddress,$x400 -Identity $identity
}