TI Map Email entity to AzureActivity

Original query, unchanged.

let dt_lookBack = 1h;
let ioc_lookBack = 14d;
let emailregex = @'^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$';
ThreatIntelIndicators
//Filtering the table for Email related IOCs
| extend IndicatorType = replace(@"\[|\]|\""", "", tostring(split(ObservableKey, ":", 0)))
| where IndicatorType == "email-addr"
| extend EmailSenderAddress = ObservableValue
| extend EmailSourceDomain = substring(EmailSenderAddress, indexof(EmailSenderAddress, "@") + 1, strlen(EmailSenderAddress) - indexof(EmailSenderAddress, "@") - 1)
| extend Url = iff(ObservableKey == "url:value", ObservableValue, "")
| extend TrafficLightProtocolLevel = tostring(parse_json(AdditionalFields).TLPLevel)
| where TimeGenerated >= ago(ioc_lookBack)
| summarize LatestIndicatorTime = arg_max(TimeGenerated, *) by Id, ObservableValue
| where IsActive and (ValidUntil > now() or isempty(ValidUntil))
| project-reorder *, IsActive, TrafficLightProtocolLevel, EmailSenderAddress, EmailSourceDomain, Type
// using innerunique to keep perf fast and result set low, we only need one match to indicate potential malicious activity that needs to be investigated
| join kind=innerunique (
    AzureActivity | where TimeGenerated >= ago(dt_lookBack) and isnotempty(Caller)
    | extend Caller = tolower(Caller)
    | where Caller matches regex emailregex
    | extend AzureActivity_TimeGenerated = TimeGenerated
)
on $left.EmailSenderAddress == $right.Caller
| where AzureActivity_TimeGenerated < ValidUntil
| summarize AzureActivity_TimeGenerated = arg_max(AzureActivity_TimeGenerated, *) by Id, Caller
| extend Description = tostring(parse_json(Data).description)
| extend ActivityGroupNames = extract(@"ActivityGroup:(\S+)", 1, tostring(parse_json(Data).labels))
| project AzureActivity_TimeGenerated, Description, ActivityGroupNames, Id, ValidUntil, Confidence, EmailSenderAddress, EmailSourceDomain, Caller, CallerIpAddress, Url
| extend Name = tostring(split(Caller, '@', 0)[0]), UPNSuffix = tostring(split(Caller, '@', 1)[0])
| extend timestamp = AzureActivity_TimeGenerated