AT&T as an internet provider and mailbox provider has been around for a while, surviving through various iterations over the years. Once upon a time (starting in 1996) that was dialup internet branded as "AT&T Worldnet," with customers being provided email addresses in the "worldnet.att.net" subdomain.
Over time, consolidation happened, and various "Baby Bell" internet providers ended up all combined into a new version of AT&T, leading toward a bunch of email domains for those other providers to now be part of the AT&T email infrastructure. (Which domains? I had long shared a list of known AT&T email domains, based on what domains I observed pointing at a particular set of mail servers.)
Fast forward from there and in 2025, AT&T email inboxes, which were partly integrated into Yahoo Mail infrastructure, became fully integrated into Yahoo's infrastructure. All of the AT&T email domains saw their DNS updated to change the MX record to point directly at Yahoo Mail's inbound email servers.
This included the email domain "worldnet.att.net." Or so I thought. At one point it was on the list of AT&T domains, and it had an MX record in DNS configured similarly to the other domains (like att.net), but at some point in the past few months, that disappeared. Poof, no more worldnet.att.net in DNS.
I'm not the only person wondering what changed there and when. A couple of commenters on my AT&T "transition complete" post asked about this as well, suggesting that their worldnet.att.net email addresses worked until some point recently (perhaps ceasing to forward mail in August 2025).
Which leads me to ask this question: Did AT&T warn email users that the "Worldnet" subdomain was going away, and when? Turns out, the answer to this is YES, way back in 2010. A bit of Googling found me this Flyertalk forum post sharing that AT&T Worldnet was shutting down as of March, 2010, and that led me to this archived AT&T help page, explaining that Worldnet was shutting down and helping users understand how they could transition their email accounts from (user)@worldnet.att.net to (user)@att.net.
It kind of looks to me like automatic forwarding of messages from the "Worldnet" subdomain to updated AT&T email accounts might have been in place from 2010 through to 2025. Fifteen years of helping keep a deprecated email address alive? That's a pretty good run, if you ask me.
Thus, if you're trying to email your friend at their worldnet.att.net address and it's now bouncing, you could try emailing the same username @ att.net instead. I'm not entirely sure if all Worldnet email accounts were automatically mapped to att.net accounts, but it's worth a shot.
And if you've long had an email address at an AT&T domain, did it go away recently? No! AT&T email domains were not retired in 2025; what changed is that the backend infrastructure has been updated to fully point at Yahoo Mail. This is nerd level server stuff that email engineers and deliverability consultants care about. The impact to you, as an AT&T email account user, should be nil. Your email account still exists, and you can still log in to it, and you can still send and receive email messages.
Bulk email senders (only) -- if you've got worldnet.att.net addresses on your email list, whoa boy, those are old, and this email subdomain is indeed no more. There's no point in attempting to send to those addresses in the future.
AT&T as an internet provider and mailbox provider has been around for a while, surviving through various iterations over the years. Once upon a time (starting in 1996) that was dialup internet branded as "AT&T Worldnet," with customers being provided email addresses in the "worldnet.att.net" subdomain.
Over time, consolidation happened, and various "Baby Bell" internet providers ended up all combined into a new version of AT&T, leading toward a bunch of email domains for those other providers to now be part of the AT&T email infrastructure. (Which domains? I had long shared a list of known AT&T email domains, based on what domains I observed pointing at a particular set of mail servers.)
Fast forward from there and in 2025, AT&T email inboxes, which were partly integrated into Yahoo Mail infrastructure, became fully integrated into Yahoo's infrastructure. All of the AT&T email domains saw their DNS updated to change the MX record to point directly at Yahoo Mail's inbound email servers.
This included the email domain "worldnet.att.net." Or so I thought. At one point it was on the list of AT&T domains, and it had an MX record in DNS configured similarly to the other domains (like att.net), but at some point in the past few months, that disappeared. Poof, no more worldnet.att.net in DNS.
I'm not the only person wondering what changed there and when. A couple of commenters on my AT&T "transition complete" post asked about this as well, suggesting that their worldnet.att.net email addresses worked until some point recently (perhaps ceasing to forward mail in August 2025).
Which leads me to ask this question: Did AT&T warn email users that the "Worldnet" subdomain was going away, and when? Turns out, the answer to this is YES, way back in 2010. A bit of Googling found me this Flyertalk forum post sharing that AT&T Worldnet was shutting down as of March, 2010, and that led me to this archived AT&T help page, explaining that Worldnet was shutting down and helping users understand how they could transition their email accounts from (user)@worldnet.att.net to (user)@att.net.
It kind of looks to me like automatic forwarding of messages from the "Worldnet" subdomain to updated AT&T email accounts might have been in place from 2010 through to 2025. Fifteen years of helping keep a deprecated email address alive? That's a pretty good run, if you ask me.
Thus, if you're trying to email your friend at their worldnet.att.net address and it's now bouncing, you could try emailing the same username @ att.net instead. I'm not entirely sure if all Worldnet email accounts were automatically mapped to att.net accounts, but it's worth a shot.
And if you've long had an email address at an AT&T domain, did it go away recently? No! AT&T email domains were not retired in 2025; what changed is that the backend infrastructure has been updated to fully point at Yahoo Mail. This is nerd level server stuff that email engineers and deliverability consultants care about. The impact to you, as an AT&T email account user, should be nil. Your email account still exists, and you can still log in to it, and you can still send and receive email messages.
Bulk email senders (only) -- if you've got worldnet.att.net addresses on your email list, whoa boy, those are old, and this email subdomain is indeed no more. There's no point in attempting to send to those addresses in the future.
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