I use KMail to report fraudalent spam mails (usually fake lotteries, nigerian scams) to abuse e-mail adresses. When I paste source of such fraudalent message which contains word/pdf attachment KMail spellchecker scans base64 encoded binary content. Because such content is long KMail is frozen till it scans all base64 content which takes few minutes. Reproducible: Always Steps to Reproduce: 1. Select any message with attachment 2. When displaying message with attachment press 'v' key to show source of message. 3. Press Ctrl+a to select all source content and Ctrl+c to copy it. 4. Compose a new message and paste (Ctrl+v) all content KMail will freeze and will remain frozen till all content will be spell checked. This will happen several times during document editing when spell checking reoccurs. Actual Results: KMail freezes until all base64 encoded attachment codes are spell checked. Expected Results: KMail should skip spell checking base64 encoded content. Base64 content is ascii encoded text stream without spaces. KMail can detect if word is longer than 20 characters then skip spellchecking it.
This bug has never been confirmed for a Kontact version that is based on KDE Frameworks, except possibly a Technology Preview version 5.0.x. Those versions differ significantly from the old 4.x series. Therefore, I plan to close it in around two or three months. In the meantime, it is set to WAITINGFORINFO to give reporters the opportunity to check if it is still valid. As soon as someone confirms it for a recent version (at least 5.1, ideally even more recent), I'll gladly reopen it. Please understand that we lack the manpower to triage bugs reported for versions almost two years beyond their end of life.
Works for me in KMail 5.5.1 on Fedora 26.