Greetings,

Limesurvey version 2.62.2+170303.

I am using my own Qmail server, which is configured with SMTP Submission + STARTTLS with self-signed certificate.

Sending invitation without TLS works fine, but when I turn on TLS nothing gets sent.

Please advise.

Currently : there are no solution , thinking it was fixed in LS official ...
Try with maildebug : you surely receive a SSL error alert (CA is not here)

Report the bug

fjenou wrote: Limesurvey version 2.62.2+170303.
Sending invitation without TLS works fine, but when I turn on TLS nothing gets sent.

Your build 170303 seems to be in the future. Please check what version/build is used.

Can be a bug in the settings of the phpmailer.
Sometimes around SMTPAutoTLS.

I would try to not use StartTLS, but use directly TLS with the SMTP-server.
Try to use TLS with port 465 instead of using StartTLS which first connects unencrypted via 25 or 587 to check if encryption is possible. If there is a bug around AutoTLS the phpmailer library will directly force encryption which won't work with Port 25 or 576. This is just an educated guess.
Port 465 is no longer standard for SMTPS, but still often used.
en.wikipedia.org/wiki/Opportunistic_TLS#SSL_ports

If it still doesn't work, you should open a bug report. It sometimes need some remarks to get the phpmailer integration with LS back on track.

@Jelo : non no : since PHP5.6 or 5.4 : all tls connexion need a valid CA (by default)

I fix it in my 2.6.2 version : github.com/SondagesPro/LimeSurvey-Sondag...e04af89a4bca062R4066

I think it was fixed in core near the same way , but : a bug not reported is a bug not fixed.

Looking at code : TLS with valmid CA or no TLS