$newUserCustomActionItemFormInfoPath = $targetList.UserCustomActions.Add()
$newUserCustomActionItemFormInfoPath.Rights = "EditListItems"
$newUserCustomActionItemFormInfoPath.Location = "CommandUI.Ribbon"
$newUserCustomActionItemFormInfoPath.CommandUIExtension = '<CommandUIExtension>
                                                                <CommandUIDefinitions>
                                                                    <CommandUIDefinition Location="Ribbon.Tabs.InfoPathListDisplayTab.Manage.Controls._children">
                                                                        <Button Id="Ribbon.Tabs.InfoPathListDisplayTab.Manage.SendItemAsMail" Alt="Nachricht versenden" Sequence="503"
                                                                             Command="sendMessageAsMailInfoPathView"
                                                                             LabelText="Send mail"
                                                                             TemplateAlias="o1"
                                                                             Image32by32="/_layouts/15/images/discoveryExport_32x32.png"
                                                                             Image16by16="/_layouts/15/images/discoveryExport_16x16.png" />
                                                                   </CommandUIDefinition>
                                                                </CommandUIDefinitions>
                                                                <CommandUIHandlers>
                                                                    <CommandUIHandler Command="sendMessageAsMailInfoPathView"
                                                                         CommandAction="javascript: msg.sharepoint.common.msgManagement.createMail(''{ListId}'', {SelectedItemId});" />
                                                                </CommandUIHandlers>
                                                            </CommandUIExtension >'

$newUserCustomActionItemFormInfoPath.Title = "Send mail"
$newUserCustomActionItemFormInfoPath.Update()