Hi,
I just installed openSuSE leap42.2 with KDE5 while I also kept Leap 42.1 with KDE4. My home partition is unchanged and is mounted to whatever system I'm booting with. Therefore the configuration files for kmail are identical. While I can send (SMTP) without any problem from kmail4 I fail doing so with kmail5. Error messages are not consistent, either "The server responded: EHLO requires valid address" or "An error occured during authentication SASL:No mechanism available". Without changing any parameters the error message is changing despite that. As I have no problem to dispatch the email with kmail4 under Leap42.1 I don't think I could confront the mail-server administration with this problem.
Thanks

------------------
Meanwhile I have experimented a bit more. I reconfigured under Leap42.1 with kmail4 die SMTP server, deleting the old one and defining the new entry. It came up with the default configuration of TLS instead of NO and it worked! Then booting to Leap42.2 with kmail5 the sending failed again as before. So that may suggest there is a bug in kamil5 if I'm not totally wrong.