I can send short e-mails without attachment without problems since Bug 388068 is solved. But always if I try to send an bigger attachment I get the following error message: Jan 07 11:38:44 franks akonadi_maildispatcher_agent[1112]: QIODevice::write (QTcpSocket): device not open Jan 07 11:38:44 franks akonadi_maildispatcher_agent[1112]: org.kde.pim.ksmtp: Socket error: 0 Jan 07 11:38:44 franks plasmashell[903]: Currrent active notifications: QHash() Jan 07 11:38:44 franks plasmashell[903]: Guessing partOf as: 0 Jan 07 11:38:44 franks plasmashell[903]: New Notification: "Das Senden der E-Mail ist fehlgeschlagen" "Fehler beim Übertragen der Nachricht. Die Verbindung zum Server ist abgebrochen." -1 & Part of: 0 Kmail and components are 17.12.0. Even if I get this error, the message including attachments is send in the background.
*** This bug has been marked as a duplicate of bug 387613 ***