Getting thunderbird email working on grapheneos

sailornev

I am currently trying to set up my university email on thunderbird on grapheneos. I already have that email account working with thunderbird on my linux laptop with the following SMTP settings:

server name: smtp.office365.com
port: 587
username: (my email)
authentication method: oauth2
connection security: starttls

When I import these settings onto my phone, i can receive emails just fine, but if I try to send them, I run into an authentication error and I can't figure out why. The emails just stay stuck in outbox and dont get sent. When I was using android before, this was not an issue.

Any help would be appreciated

Thanks!

de0u

sailornev When I import these settings onto my phone, i can receive emails just fine, but if I try to send them, I run into an authentication error and I can't figure out why.

Does the error include any text beyond "authentication error"?

sailornev

de0u
I get 2 notifications:

Failed to send some messages
Authentication unsuccessful
[BL1PR13CA0340.namprd13.prod.outlook.com 2025-09-01T13:04:36.305Z 08DDE84F8D3B37FC]

and

Authentication failed
Authentication failed for [my email].
Update your server settings.

n3t_admin

sailornev that sounds like you either entered incorrect credentials or the Outlook instance uses a different authentication method (like OAuth 2.0 for example).

sailornev

as far as I know, I'm using the correct authentication (OAuth 2.0), security and port (starttls on 587) and server (smtp.office365.com) and all these are the same as on my laptop. The only field available that I dont understand is client certificate, which is currently set to none, but there are no other available options. Is this correct?

n3t_admin

sailornev can you try port 465 instead? Either that or set connection to SSL/TLS instead. Are you sure you entered the correct credentials for IMAP and SMTP?

avaluedcustomer

Are you using private DNS or some ad-blocker that might block the communication to the mail server?

sailornev

avaluedcustomer

I don't think so, unless there is anything already installed with grapheneos.

sailornev

using ssl/tls on 465 is not working. I'm pretty sure I dont need to change anything with my IMAP settings as I am receiving emails just fine, but my settings are:

server: outlook.office365.com
security: ssl/tls
port: 993
authentication: oauth 2.0
username: [my email]
client certificate: none

Again, my smtp settings are exactly the same as on my laptop, which sends email just fine. I dont know what the problem is.

n3t_admin

sailornev hmm, best thing I can recommend is to check the official docs from MS.
I am by no means an Outlook expert and don't know how they do things (I tend to stay as far away from Microsoft products as possible). Another option you could try, is to use a different mail client like FairEmail and see if it works there. Sorry I can't be of more help :/

sailornev

I just tried setting up fair email, and it can send/receive messages just fine with the same settings. I much prefer the ui of thunderbird though :(. I highly doubt its a microsoft issue though, given that other services can send email just fine, I'm just unsure what or where the issue might be.

n3t_admin

sailornev I would honestly just file a bug report. I don't think this is caused by your settings, but rather the implementation of K9-Mail/Thunderbird.

sailornev

ok, thanks. will do