4 ms·

As former Exchange admin/Office365, it's using EWS (Exchange Web Services) which is being removed in October 2026 for Office365. So for most, this is extremely

As former Exchange admin/Office365, it's using EWS (Exchange Web Services) which is being removed in October 2026 for Office365. So for most, this is extremely time limited. EDIT: EWS continues to be supported for on premises Exchange and is not scheduled for deprecation.

trympet 11mo ago
How do you know Thunderbird is using EWS, not MAPI? MAPI is not going away any time soon.
- sjoerger 11mo ago
  Read the docs? https://blog.thunderbird.net/2025/11/thunderbird-adds-native-microsoft-exchange-email-support/ https://blog.thunderbird.net/2025/11/thunderbird-adds-native...
  - trympet 11mo ago
    Yikes, thanks. Enjoy this feature while it lasts, I guess. EWS is getting nuked.
- stackskipton 11mo ago
  Read the article?
drannex 11mo ago
> it's using EWS (Exchange Web Services) which is being removed in October 2026 for Office36 This is Microsoft we're talking about here, so if its slated for removal in Oct '26, it will be put into LTS, and finally 'retired' (but operational) _starting_ around 2031.
- stackskipton 11mo ago
  Microsoft swears it's happening: https://techcommunity.microsoft.com/blog/exchange/retirement-of-exchange-web-services-in-exchange-online/3924440 https://techcommunity.microsoft.com/blog/exchange/retirement... Take the blog article for what you will. I have noticed in Office365, they tend to be less backward compatible than you would expect from Microsoft.
  - godelski 11mo ago
    > Microsoft swears it's happening And when has that ever meant it comes without delay?
    - stackskipton 11mo ago
      Up to you if you believe Microsoft or not. I don't really care, I haven't messed with 365 outside being end user in years.
    - dijit 11mo ago
      to be fair with you, EWS has been deprecated since I think 2014, so we're already in the "pushed" window.
  - ocdtrekkie 11mo ago
    As an on-prem admin, I am blown away that there's 30-40 changes to 365 monthly, often including at least two or three feature deprecations. It seems like building a building on top of quicksand.
- userbinator 11mo ago
  The new Microsoft is unfortunately not like the old one.
- hobofan 11mo ago
  The have been keeping to the timeline when it comes to other recent Exchange Online removals (certain auth roles).
amaccuish 11mo ago
As you imply though, it remains for on-premise. They're working on msgraph as well luckily.
- stackskipton 11mo ago
  I updated my post to reflect yes, this is Office365 only. On premise will continue to support EWS. Depending on where you are, Exchange on premise is becoming extinct.
aorth 11mo ago
The Thunderbird blog post also mentions they are looking to support the Microsoft Graph. More limiting is that the current release doesn't support custom Office365 tenant IDs. So basically, unless you are using outlook.com this won't currently work yet. I'm lucky that my org hasn't disabled SMTP and IMAP, but it's been so slow lately...
- bangaladore 11mo ago
  Someone might be wondering why someone might have different URLs. One example is anyone under sovereign clouds (eg. GCC, GCC-High) which use different URLs (and TLDs) across the board (eg outlook.office365.us)
gerdesj 11mo ago
You'll recall how horrendous on prem Exchange updates could be. Surely the sheer amount of time involved was a nudge and nothing technical? My tiny company had an on prem Exchange, migrated from GroupWise, and is now cloudy. I did all the migrations myself. I have left things with our MX records pointing to on prem (Exim + rspamd + stuff) and relaying to MS 365 and a few IMAP daemons. If MS take the piss with licensing costs, I'll simply relay elsewhere and drop them. Then I'll migrate my customers away. It'll take a while but it is not insurmountable. FWIW: I use Evolution on my Kubuntu based gear to access M365 email. Wifey rocks Arch and I've deployed Evo on KDE there too.

trympet 11mo ago

How do you know Thunderbird is using EWS, not MAPI? MAPI is not going away any time soon.

sjoerger 11mo ago
Read the docs? https://blog.thunderbird.net/2025/11/thunderbird-adds-native-microsoft-exchange-email-support/ https://blog.thunderbird.net/2025/11/thunderbird-adds-native...
- trympet 11mo ago
  Yikes, thanks. Enjoy this feature while it lasts, I guess. EWS is getting nuked.
stackskipton 11mo ago
Read the article?

drannex 11mo ago

> it's using EWS (Exchange Web Services) which is being removed in October 2026 for Office36 This is Microsoft we're talking about here, so if its slated for removal in Oct '26, it will be put into LTS, and finally 'retired' (but operational) _starting_ around 2031.

stackskipton 11mo ago
Microsoft swears it's happening: https://techcommunity.microsoft.com/blog/exchange/retirement-of-exchange-web-services-in-exchange-online/3924440 https://techcommunity.microsoft.com/blog/exchange/retirement... Take the blog article for what you will. I have noticed in Office365, they tend to be less backward compatible than you would expect from Microsoft.
- godelski 11mo ago
  > Microsoft swears it's happening And when has that ever meant it comes without delay?
  - stackskipton 11mo ago
    Up to you if you believe Microsoft or not. I don't really care, I haven't messed with 365 outside being end user in years.
  - dijit 11mo ago
    to be fair with you, EWS has been deprecated since I think 2014, so we're already in the "pushed" window.
- ocdtrekkie 11mo ago
  As an on-prem admin, I am blown away that there's 30-40 changes to 365 monthly, often including at least two or three feature deprecations. It seems like building a building on top of quicksand.
userbinator 11mo ago
The new Microsoft is unfortunately not like the old one.
hobofan 11mo ago
The have been keeping to the timeline when it comes to other recent Exchange Online removals (certain auth roles).

amaccuish 11mo ago

As you imply though, it remains for on-premise. They're working on msgraph as well luckily.

stackskipton 11mo ago
I updated my post to reflect yes, this is Office365 only. On premise will continue to support EWS. Depending on where you are, Exchange on premise is becoming extinct.

aorth 11mo ago

The Thunderbird blog post also mentions they are looking to support the Microsoft Graph. More limiting is that the current release doesn't support custom Office365 tenant IDs. So basically, unless you are using outlook.com this won't currently work yet. I'm lucky that my org hasn't disabled SMTP and IMAP, but it's been so slow lately...

bangaladore 11mo ago
Someone might be wondering why someone might have different URLs. One example is anyone under sovereign clouds (eg. GCC, GCC-High) which use different URLs (and TLDs) across the board (eg outlook.office365.us)

gerdesj 11mo ago

You'll recall how horrendous on prem Exchange updates could be. Surely the sheer amount of time involved was a nudge and nothing technical? My tiny company had an on prem Exchange, migrated from GroupWise, and is now cloudy. I did all the migrations myself. I have left things with our MX records pointing to on prem (Exim + rspamd + stuff) and relaying to MS 365 and a few IMAP daemons. If MS take the piss with licensing costs, I'll simply relay elsewhere and drop them. Then I'll migrate my customers away. It'll take a while but it is not insurmountable. FWIW: I use Evolution on my Kubuntu based gear to access M365 email. Wifey rocks Arch and I've deployed Evo on KDE there too.