Windows 11, Mailspring Version 1.17.2-a312df89, paid account
OS and Version:
Installation Method:
Mailspring Version:
Additional Context
IMAP login succeeds.
Same credentials work in Thunderbird immediately.
Issue began after today’s MailSpring update.
Rolling credentials or server changes do not resolve.
Update: Rolling back to the previous MailSpring version immediately restores SMTP AUTH and outbound mail across all affected accounts. Confirms this is a regression introduced in 1.17.2, not a server or credential issue. Auto-updates disabled pending fix.
Same here on Ubuntu. SMTP AUTH is broken with 1.17.2 . Rollback to 1.17.1 fixes it.
I hoped this update would fix the bug that the window doesn’t open on Wayland, but that also doesn’t work. SMTP Auth is kind of the basic things a mail client should do, why wasn’t this tested?
I didn’t find a way to disable the annoying auto-update. At the moment, I just avoid closing Mailspring and keep the setup for the previous version nearby
Download the 1.16.0 setup from GitHub, run it and do not close Mailspring to avoid auto-update. No need to uninstall the current version. No data will be lost
For me, Mailspring checks and downloads the update, but it does not install unless I explicitly click “Restart and Update.” I just dismiss the prompt. I’ve quit and relaunched multiple times and it stays on the rolled-back version.
So I haven’t disabled updates — I’m just refusing the install step.
Same problem here but I don’t think it’s specific to STARTTLS – if I go into connection settings I get the same error trying to “Connect Account” regardless of whether I’m using STARTTLS or SSL/TLS (my SMTP provider offers both on different ports). The mailspring logs at this point don’t really indicate what it is doing or what went wrong:
----------SMTP----------
220 cmr-tmc.i-09cb16b117244b5cf - SMTP Ready
OpenSSL version: OpenSSL 3.6.0 1 Oct 2025
init
EHLO peacock
250-cmr-tmc.i-09cb16b117244b5cf Hello [REDACTED]
250-SIZE 83886080
250-8BITMIME
250-DSN
250-PIPELINING
250-PIPECONNECT
250-AUTH LOGIN PLAIN
250-CHUNKING
250-STARTTLS
250-SMTPUTF8
250 HELP
SASL_PATH:
SMTP Last Response Code: 250
SMTP Last Response: cmr-tmc.i-09cb16b117244b5cf Hello [REDACTED]
SIZE 83886080
8BITMIME
DSN
PIPELINING
PIPECONNECT
AUTH LOGIN PLAIN
CHUNKING
STARTTLS
SMTPUTF8
HELP
mailsmtp Last Error Code: 296
mailsmtp Last Error Explanation: Unknown
mailsmtp Last Error Location: 10
mailsmtp Last Auth Type: 2
I can replay this SMTP conversation manually using openssl s_client without noticeable issues and definitely no error code 296. I had to make some guesses about what mailspring is sending because the log is ambiguous, here I’ve used > and < to disambiguate what I am typing vs. what the server is sending.
< 220 cmr-tmc.i-026f6d89b085f731a - SMTP Ready
> OpenSSL version: OpenSSL 3.6.0 1 Oct 2025
< 500 unrecognized command
> init
< 500 unrecognized command
> EHLO peacock
< 250-cmr-tmc.i-026f6d89b085f731a Hello [REDACTED]
< 250-SIZE 83886080
< 250-8BITMIME
< 250-DSN
< 250-PIPELINING
< 250-PIPECONNECT
< 250-AUTH LOGIN PLAIN
< 250-CHUNKING
< 250-STARTTLS
< 250-SMTPUTF8
< 250 HELP
... «at this point the server is just waiting for me to do something else»
... «eventually it times out»
< 421 Adios Amigo
Same problem here with the Mailspring version 1.17.2. The imap works and i have problems with smtp with four different email accounts. No matter what i tried situation did not resolve. I expect developers release a solution soon.
I have very similar problem. Can not authenticate to SMTP with TLS with correct password. IMAP does work correctly. But because of SMTP error I can’t complete account configuration setup. I just tested my password manually with openssl s_client:
Update.exe is in C:\Users\user\AppData\Local\Mailspring\app-1.16.0 in my case. Whenever this bug is solved you will be able download the new MailSpring version and installation will create a new folder like app-1.18.0 with a new update.exe so that the update process is restored.
