Do you mean compact?

"komprimera" in swedish is compress in english. Suggest you translate correctly to begin with. In YOUR term it should be "compact". It seems like it remves lots of mails in a random manner in my folders.

I do not do translations. If you wish to discuss it I suggest you contect those doing the translations. https://wiki.mozilla.org/L10n:Teams:sv-SE/en#Swedish_.28sv.2C_sv-SE.29

Assuming it is compact, there is often issues of perceived data loss from compact, but it is rarely the case.

When you delete an email in Thunderbird that email is marked as deleted, but the file it is in does not have the data removed. It is ignored by the program. Over time the number of emails that are deleted but not removed rises and there must be a process to rewrite the storage file both form the perspective of freeing space but more importantly to actually purge the date folk think they have already deleted.

When the new file is written the index to that file is also fully recreated. It is at this point that apparent data loss occurs as the pre existing index has become out of sync with the data for some reason and the new file just does not have the data to support the only index.

Perhaps before you compact, try right clicking the folder and selecting repair first. If you mail disappears then. It is not the compact process that is at fault.

If you can demonstrate real data loss. Please file a bug. Preferably with before and after MBOX files for the folder. (you will need to backup your profile folder to have a before. Thunderbird does not keep one after it successfully completes the compact process. If it is not successful the new file appear in Thunderbird as an NS Temp folder.

there no such function as "repair" in the swedish version (translated or untranslated). It is good to know that email disappears since that confirms my own observation. It looks like I will have to go back to Outlook after all. Losing email is not an option.

Perhaps you need someone to speak Swedish to you. Because your conclusions are based on nothing I said. I offered you the opportunity to file a bug if you could demonstrate data loss. Personally I do not believe you can, but I was not rude I offered you the chance to prove it. You then jump to a conclusion that is entirely unsubstantiated.

Every version of Thunderbird for years has had the properties repair arrangements. Here is the English version. When you find the dialog, please post a copy of it minus the repair button.

tks for gicing me the proper guidance. Now I found, but not where I exepcted it to be. I executed that one and a few mails has returned. THANKS.