After some testing using KDE 4.3 in Kubuntu karmic I can now confirm that Malte's fix works also for kmail. In fact, all kio slaves (like kio_http, kio_smtp) that use the KTcpSocket class correctly support with this fix self-signed certificates. Kmail correctly uses the certification list that is connected by the symbolic link fix. See extract of the debug log: kmail(20529) KMComposeWin::doSend: Plain text kmail(20529) KMComposeWin::doSend: Calling applyChanges() kmail(20529) KMComposeWin::applyChanges: Entering kmail(20529) MessageComposer::applyChanges: KMAIL_DEBUG_COMPOSER_CRYPTO = FALSE kmail(20529) MessageComposer::breakLinesAndApplyCodec: Added an on the last line kmail(20529) MessageComposer::breakLinesAndApplyCodec: Added an on the last line kmail(20529) MessageComposer::composeMessage: Starting to compose message kmail(20529) MessageComposer::composeMessage: mEarlyAddAttachments= false mAllAttachmentsAreInBody= false kmail(20529) MessageComposer::addBodyAndAttachments: Set top level Content-Type from originalContentTypeStr()= "Text/Plain; charset="us-ascii"" kmail(20529) KMComposeWin::slotContinueDoSend: true kmail(20529) KMFolderMaildir::addMsgInternal: FolderStorage::msgStatusChanged kmail(20529)/kmail (storage internals) KMFolderMaildir::getDwString: KDE_fopen(abs_file= "/home/solkraftwerk/.kde/share/apps/kmail/mail/outbox/cur/1264549308.20529.6aSVn" , "r") == stream == 0x289af80 kmail(20529)/kmail (storage internals) KMFolderMaildir::getDwString: fclose(mIndexStream = 0x289af80 ) kmail(20529)/kdepimlibs (mailtransport) MailTransport::Transport::Transport: "1254495839" kmail(20529)/kio (Slave) KIO::Slave::createSlave: createSlave "smtp" for KUrl("smtp://