By July, Verizon will block users from accessing Yahoo & Tumblr using AT&T email addresses

In a move that’s sure to rattle net neutrality supporters and potentially points to a walled-garden future for TechCrunch’s parent company Oath (and its parent Verizon), Yahoo services and Tumblr (both Oath properties) will no longer let users log in with an AT&T email address (or any of its subsidiary service providers).

AT&T is a competitor to Verizon.

In a notice that was posted online Sunday, Tumblr advised its users that:

Starting on June 30, 2017, att.net customers will no longer be able to log in to their Yahoo and Tumblr accounts through email addresses with the following domains: att.net, ameritech.net, bellsouth.net, flash.net, nvbell.net, pacbell.net, prodigy.net, sbcglobal.net, snet.net, swbell.net, and wans.net.

Affected customers will have to update their email addresses to something with a different domain.

The move speaks to a broader antipathy toward openness among the big service providers as they try to carve out space with more proprietary offerings.

It’s a stratagem, though, that seems a bit excessive, and one that could be especially damaging to a Tumblr community that was a vocal advocate for net neutrality and a free and open internet.

Already, media outlets like The Verge are reporting that the newly acquired Tumblr may be under pressure to be less vocal in its support for net neutrality — something which has current and former staff members chafing.

For anyone affected, here’s how to change an email address to something more suitable to Oath:

1. In a web browser, click “Settings” under the account menu at the top of the dashboard (looks like a person’s silhouette).
2. To the right of your email address, click the pencil icon.
3. Update the email address and confirm your password.
4. Save your changes.

Verizon might want to tread carefully with this decision. Tumblr is a valuable property and poking its community could wind up costing the company one of the more interesting assets it had picked up with the Yahoo deal. Certainly the company wouldn’t want to do anything to alienate its users further.

Oath has not responded to a request for comment.