SSL error 48

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Joined: November 22nd, 2017, 10:00 am

Post Posted November 22nd, 2017, 6:26 pm

I don't need help, but I thought I'd post this here in case others had trouble.

Recently, I had to help a user setup Thunderbird to read IMAP email and send SMTPS on our server. The IMAP worked fine, but the SMTPS didn't. He got a non-descript error that was no help at all.
Could not be sent using outgoing server SMTP for an unknown reason.

Verify server settings and try again.

On the server side, there was more useful detail.
Nov 22 01:56:17 mail postfix/smtpd[48660]: connect from[]
Nov 22 01:56:17 mail postfix/smtpd[48660]: Anonymous TLS connection established from[]: TLSv1.2 with cipher ECDH
E-RSA-AES128-GCM-SHA256 (128/128 bits)
Nov 22 01:56:17 mail postfix/smtpd[48660]: warning: TLS library problem: error:14094418:SSL routines:SSL3_READ_BYTES:tlsv1 alert unknown ca:/usr/src/secure
/lib/libssl/../../../crypto/openssl/ssl/s3_pkt.c:1315:SSL alert number 48:
Nov 22 01:56:17 mail postfix/smtpd[48660]: lost connection after CONNECT from[]
Nov 22 01:56:17 mail postfix/smtpd[48660]: disconnect from[] commands=0/0

I installed Thunderbird (52.4.0) on my Mac (10.13.1) laptop, and I was able to send email using his account. So, I installed Thunderbird (52.4.0) on my Windows (10) desktop. There I was able to reproduce the error. So, I knew the problem was something related to Windows.

I did a bunch of googling for the error string and didn't find much useful. But then, I searched for "SSL error 48" and came across this page.

I purchased and installed the utility and ran it on the Windows desktop twice. Each time, after the scan completed, I rebooted the desktop.

That fixed the problem. So, it has something to do with system files or registry settings in Windows. Hopefully, this information will be useful to someone.


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Posts: 44480
Joined: July 30th, 2003, 5:06 pm

Post Posted November 23rd, 2017, 7:04 am

Thanks for sharing that. ... 80255.html and ... unknown-ca seem to describe the same SSL error. The problem is that the client does not trust the servers certificate. Importing the appropriate CA certificate frequently solves the problem. That can take some research.

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