Okay, something is weird. I have Outlook.com email with custom domain (previously Windows Live Domains). These kind of accounts had problems with Nylas since forever (see my old GitHub issue - https://github.com/nylas/nylas-mail/issues/859). I have tried adding it to new Nylas app with Office 365/custom IMAP with no success.

The weird thing is, in last 15 minutes someone from USA - AWS instance, 35.167.235.231 - tried to connect to my account. This app is said to sync locally, right? But I see no attempts from my IP in Outlook.com panel, but about ten from AWS. All of these started when I installed Nylas and tried to configure it; remaining logins logged by Microsoft are 100% by me (web client, iPhone Mail.app). WTF?

edit: https://a.pomf.cat/gxhabs.png

2nd edit: According to https://github.com/nylas/nylas-mail/issues/3405#issuecomment... someone else is unable to connect with GMail because of Nylas servers throwing HTTP 502. Does it sync locally or through Nylas' AWS instances? Is this why I can't configure my account with IMAP?

I've been looking forward to trying this out, no good mail clients on Linux

Stuck on "Still trying to reach Nylas..." (https://a.pomf.cat/sxiair.png). Good.

edit: Looks like it tries to fetch some PNG file, but all it gets is HTTP 502, I guess. (https://a.pomf.cat/xiblzy.png)