Google's /url redirector, and email

I don’t know if you’ve seen these in your email recently, but I have.

Instead of someone writing:

Come and visit at https://example.com

…they end up writing:

Come and visit at https://www.google.com/url?q=https://example.com&source=gmail&ust=1792084319793000&sa=E

This looks odd. So…

What’s going on?

This is a redirect link from Google. You can see where it’s going, but it pops through Google first, just in case there’s something naughty going on. If there is, Google can stop these links working for that particular domain.

Why are they doing this?

Your email program is unlikely to mark a link to Google as spam. And perhaps that’s all it checks?

What’s the UST parameter?

It’s a timestamp.

1792084319793000 = a microseconds timestamp. This particular one is Thu Oct 15 2026 17:11:59 GMT+0000

This email was sent on Wed, 14 Oct 2026 17:12:01 GMT+0000

It appears to be set to a time that’s exactly 24-hours after the email was sent. Not composed - but sent. It’s unlikely that a human would compose this email and send it within two seconds; and if there are more than one URLs in the email treated in this way, they all have exactly the same ust parameter.

I’m guessing this is used as a method of checking how fresh the link was. But, you can edit the ust to say anything you like. A ust of “1” is just fine.

What’s adding them?

Almost all (but not all) of the emails I’ve been sent with these URLs in them have a message header that says…

Received: from 101988054943 named unknown by gmailapi.google.com with  HTTPREST; Fri, 9 Oct 2026 14:15:49 -0500

That means that these emails are being sent via the Gmail API - not the Gmail website itself, which has a different line in message headers.

I asked people what they used to send it. One person responded and told me.

They used Claude for help with the email.

And, yes, Claude specifically can connect to Gmail.

Is it Claude then?

Probably. Or one of Claude’s friends.

Is it now possible to filter emails sent by AI agents into a different inbox?

Yeah, maybe. Perhaps checking for google.com/url within the email; but also for gmailapi.google.com within the message headers? It looks possible to write a sieve filter to achieve that.