Difference on number field on sys_watermark table default value

[gazalagrawa]

I found there is a difference in default value of number field of sys_watermark table. Both are at OOB version, when I changed it, it stopped evening receiving email on the instance. What does this difference mean? What configuration do I need to do to make it working such that email having same watermark in sub/body should be considered as Reply not new.

Working instance:

Instance with issue

[gazalagrawa]

YEs the email never reached the instance, it is happening only if I am using one of the above approaches and using ref tag as a new email. (altering subject)

Reply and forward works fine.

[Naveen20]

Not a watermark generation issue; it's the OOB Inbound Email Filters dropping the message before it comes in sys_email

Most likely: If you are sending the test email from another ServiceNow instance, the outbound email carries the header X-ServiceNow-Generated: true. The receiving instance's OOB "Ignore Header" inbound email filter discards it — the email never appears in the email log or sys_email. The two recent community threads on this confirm the behavior.

Verify and fix:

1. Check the Junk folder first: System Mailboxes > Junk (also filter sys_email for Type = received-junk or received-ignored).

2. Inbound Email Filters: System Policy > Email > Inbound Email Filters — open the Ignore Header filter. Default condition matches X-ServiceNow-Generated. Add an exception (e.g., specific sender domain) rather than disabling the filter wholesale.

3. Other filters to review in the same list: Ignore Sender (your own outbound address), Ignore Subject (auto-reply patterns).

4. If you're testing by sending FROM the same instance TO itself, that's also blocked by glide.pop3readerjob.process_messages_with_self_email_address — set to true only for testing, never in prod (creates loops).

Test from a plain mailbox (Gmail/Outlook) without the SN header — it should come normally.