HCL got a big Friday the 13:th problem, due to a bug created back in early days of the Domino server when no one saw anything beyond 5 years ahead as a potential problem. Simplified what I’ve read is that a limit in an calculation formula for epoch dates created this problem that made the function return -1 instead of an incremental number, a complete writeup will come later from HCL in the technote.
This makes the mail routing to stop working if you have more than one mailbox, routing between servers to get to the internet. Read the technote here it’s updated continuously and if you can apply the hotfixes do so.
https://support.hcl-software.com/csm?id=kb_article&sysparm_article=KB0118192

HCL is as always quick on the problem and did within 24 hours identify the problem and did release fixes for the domino versions that is active in maintenance now. A big shoutout to all developers that has worked to getting this out so fast for version 11,12 and 14 (Fixes is uploaded where you can download other fixes), if you still are on version 9 or 10 you could get a fix if you are on an extended support plan by opening a support ticket.
So for most companies that has servers that is on any earlier version than 11 might have potential problems with mail routing and server mail rules.
My initial findings is that if you only have one server, one mail.box no mail rules you are not affected by mail deliver problems, it could be other things that stops working other than mail rules because the problem makes settings not being loaded from the config.
NO PANIC FOR ADMINS with the above config regarding mail delivery
(comment if you have found something)

I usually like to try checking out if there is an workaround, I started to check if there was a notes.ini parameter to set Max mail hops but I couldn’t find that one.

Then I switch over to check what the problem was and found that removing all extra mail.box databases so you only have one (mail.box). This makes the emails being sent out if you run the send agent on that server, that fixes some of the problems.

Emails being routed from other servers only routes one server from the sent server and then gets stuck. But if I use release held email they are being routed. Hmmm, so I created an scheduled agent in another database and check for emails in the mail.box that has the specific attributes and the field $hops set to 0.
That actually releases and sends the emails in my environment, It doesn’t solve problems with mail rules and potential everything but some is my findings. It needs to be on all servers that get emails from other servers sent to them to be routed.

Of course the hotfixes from HCL is always the best to apply but if you don’t have the possibility this might help you temporary to get this working with mail routing without the hotfixes for a while, until you can upgrade the server.

Adam wrote a good post about ways to get the patches with / without your agreement with HCL. http://ab1osborne.blogspot.com/2024/12/your-support-options-for-friday-13th.html?m=1
If you are located in Sweden and have licensing questions feel free to reach out to me thru this page or thru my company QNOVA if you are located in some other part of the world check out the partner locator

Another this that has come up is that because the problem makes the server go back to 1 mailbox and the fix is using the correct number again. Remember that emails can then be stuck in mail.box that you need to copy over to one of the active boxes after the patch.
Also you need to have “Hold undeliverable mail” set to enable

Older version of the nab template

If the interim installer is failing with the error message “Notes/Domino related process is still running” – see Installing FixPack/Hotfix on Windows fails due to Windows Management Instrumentation Service KB0038497
https://support.hcl-software.com/csm?id=kb_article&sysparm_article=KB0038497

This is the code I have in the extra database with the scheduled agent. ( You can’t add it to mail.box )
This code is used a your own risk, without any HCL support and it will NOT fix all problems related to this bug.

Dim session As New NotesSession
	Dim mailboxdb As New NotesDatabase(session.Currentdatabase.server,"mail.box")
	Dim v As NotesView
	Dim doc As notesdocument
	If mailboxdb.Isopen Then
		Set v=mailboxdb.Getview("mail")
		Call v.Refresh()
		v.Autoupdate=false
		Set doc=v.Getfirstdocument()
		Do While Not doc Is Nothing
		   If Not doc.hasitem("hopsretry") Then
			If doc.Getitemvalue("RoutingState")(0)="HOLD" Then
				If CStr(doc.Getitemvalue("$hops")(0))="0" then
				Call doc.Replaceitemvalue("RoutingState","")
			Call doc.Removeitem("SaveOptions")
		       If doc.Hasitem("RoutingState") And 
                      Not doc.getitemvalue("RoutingState")(0)="" Then
						'Keep Form
			Else
		If doc.Hasitem("MailSavedForm") And 
                 Not doc.getitemvalue("MailSavedForm")(0)="" Then
	 Call doc.Replaceitemvalue("Form",doc.Getitemvalue("MailSavedForm"))
		ElseIf doc.Hasitem("AppointmentType") Then
		 Call doc.Replaceitemvalue("Form","Notice")
		Else
		 Call doc.Replaceitemvalue("Form","Memo")
						
		End If
		End If
			Call doc.Replaceitemvalue("$Hops",25)
			Call doc.Removeitem("RoutingStateBy")
			Call doc.Replaceitemvalue("hopsretry",1)
			Call doc.save(True,False)
		End if
		End If
		End If
		Set doc=v.Getnextdocument(doc)
		Loop
              End if