Fix email ingestor: treat dates slightly in the future correctly

There was a logic which tried to prvent future dates because of some
artifacts in old mboxes, but this caused issues with timezones and
missing timezone handling.

That is now fixed even for mboxes, but for the imap ingestor we simply
accept the date as is.

Author: dutow

app/services/email_ingestor.rb

@@ -1,13 +1,13 @@
 # frozen_string_literal: true
 
 class EmailIngestor
-  def ingest_raw(raw_message, fallback_threading: false)
+  def ingest_raw(raw_message, fallback_threading: false, trust_date: false)
     m = Mail.new(raw_message)
 
     message_id = clean_reference(m.message_id)
     message_id = nil if message_id.blank?
     return nil unless message_id
-    sent_at = sanitize_email_date(m.date, m[:date], message_id)
+    sent_at = trust_date ? m.date : sanitize_email_date(m.date, m[:date], message_id)
 
     body = normalize_body(extract_body(m))
     existing_message = Message.find_by_message_id(message_id)
@@ -302,10 +302,17 @@ def add_mentions(msg, users)
   end
 
   def sanitize_email_date(mail_date, mail_date_header, message_id)
-    current_time = Time.now
-    return mail_date if mail_date.nil? || (mail_date >= Time.parse('1996-01-01') && mail_date <= current_time)
+    return mail_date if mail_date.nil?
+
+    current_time_utc = Time.now.utc
+    mail_date_utc = mail_date.utc
+    min_valid_date = Time.parse('1996-01-01 00:00:00 UTC')
+    future_tolerance = 24 * 3600
+
+    if mail_date_utc >= min_valid_date && mail_date_utc <= current_time_utc + future_tolerance
+      return mail_date
+    end
 
-    original_date = mail_date
     sanitized_date = mail_date
 
     if mail_date_header && mail_date_header.to_s =~ /\b(\d{2})\s+\w+\s+(\d{2,4})\b/
@@ -320,7 +327,7 @@ def sanitize_email_date(mail_date, mail_date_header, message_id)
       end
     end
 
-    if sanitized_date > current_time || sanitized_date.year < 1996
+    if sanitized_date.utc > current_time_utc + future_tolerance || sanitized_date.year < 1996
       sanitized_date = Time.parse('2000-01-01 00:00:00 UTC')
     end
 

app/services/imap_idle_runner.rb

@@ -149,7 +149,7 @@ def process_uid(uid)
     msg = nil
     ActiveRecord::Base.transaction do
       msg = instrument('ingestor.ingest', uid: uid) do
-        @ingestor.ingest_raw(raw)
+        @ingestor.ingest_raw(raw, trust_date: true)
       end
     end