Unable to send or receive btinternet.com emails over AT&T’s mobile data network

[FraserAl]

My UK EE plan provides very limited US data roaming capability so I purchased an AT&T prepaid mobile plan that gives me 15Gb of 5G data plus voice calls & SMS messaging. The AT&T SIM is in my iPhone Xs (iOS 14.8) and everything is working as normal apart from one thing: Apple’s Mail app is unable to connect to my btinternet.com email address (BT Premium email). All of my other email accounts (icloud.com, gmail.com, outlook.com and mailasail.com) are working as normal.

I can access my btinternet.com email via BT webmail on Safari from my iPhone while connected to the internet via AT&T’s mobile data network.

I can also access my btinternet.com email from my iPhone’s Mail app if it is connected to the internet via my hotel’s or a restaurant’s wifi (rathe than via the AT&T mobile data network).

Further, if I use my iPhone as a hotspot for my MacBook, the MacBook’s Mail app is unable to connect to the btinternet.com server while all of my other email accounts continue to work fine. And if I connect the MacBook to the internet by wifi, the btinternet.com email account starts working agin.

So there seems to be a very specific problem where both of my Apple Mail apps (iOS and macOS) are unable to connect to the btinternet.com email servers if the device’s connection to the internet is over the AT&T mobile data network.

I’ve tried AT&T’s technical support and the AT&T user forums but no joy there.

Can anyone out there in the BT community suggest what might be going wrong and how to resolve this problem.

Thank you in anticipation.

[gg30340]

Can you access your email using your EE roaming and do you know which mobile network it connects on?

For the purposes of trying to diagnosis if it is an AT&T,  Apple Mail App or a BT problem have you tried a different email app such as Blue Mail?

[FraserAl]

Here are the follow up results.

With my UK EE SIM in the iPhone, it connected to the T-Mobile network and my btinternet.com email started working. Further, when I enabled the iPhone as a hotspot and connected my MacBook to it,  btinternet.com email on my MacBook also started working. When I replace the UK EE SIM with my US AT&T SIM, the btinternet.com email problem comes back on both the iPhone and the MacBook.

I have also activated a T-Mobile SIM that is in a Huawei mobile wifi device from a previous trip to the US. I don’t have any problems getting through to my btinternet.com email from either my iPhone or my MacBook if I am connected to the internet via the Huawei mifi device.

I also gave BlueMail a try. I was unable to set up my btinternet.com email account when connected via the AT&T mobile data network but had no problems when connected via T-Mobile.

My conclusion from these additional tests is that the problem is specific to the AT&T mobile data network and how it connects to the btinternet.com servers.

In the interim I did receive a reply from AT&T technical support pointing me to this site which sets out AT&T’s understanding of the email app settings for numerous email providers: https://www.att.com/support/article/email-support/KM1070521.

It looks as though AT&T’s info for BT is out of date because they say the incoming IMAP server should be imap.mail.yahoo.com and that SSL should be off. I did give it a try but the iPhone’s Mail app was unable to establish a connection with the server during verification. (Connected via T-Mobile at the time.) I’m going to let AT&T know their information is out of date and ask them to investigate whether there is anything they need to do to their network config following BT’s split with Yahoo.

Any other thoughts on where to go from here?

[gg30340]

The problem would appear to be with AT&T and how it is interacting or not with BT.

The correct settings are as per this link but as your email works on other networks they must be correct.

https://www.bt.com/help/email/manage-email-account/manual-settings/what-are-the-settings-for-outgoin...

I think there is nothing more I can suggest other than ask for a refund for your sim and don't use AT&T

[FraserAl]

Thanks for the confirmation. I'm getting some value from the AT&T plan so I'll just put the service I'm not getting down to experience.

I'll post an update if I get anywhere with AT&T doing something at their end.