Hello, My boss, (small family business) insists on using Thunderbird for the business. He sends and receives hundreds of emails every day. Often times has 20+ email tabs open at the same time. It's become such a problem that I have purchase larger SSD drive because he was always running out of storage space on his PC. His Thunderbird file is currently over 12 gig. The main issue is: He will have several emails open and will start to reply to a customer. When he hits reply, the body of the email references data from an really OLD previous email that was either archived or deleted. Most of the time these are emails that were previously deleted. Then he goes back to his Inbox to try to find the original message and it cannot be found and is missing. He then finds the original email on his iPhone Inbox (Same Email Account - IMAPED to his phone) then forwards it to himself, in order to obtain the original contents of the message again. Sometimes the reply box has data from multiple old emails! It's hard to explain. This goes on and on and he's driving me nuts, as I'm the local "Mr. IT Fix it." for the company. Although, I have no formal degree or training in such things. My background is in Accounting. LOL From reading other forums, this appears to be either an IMAP Indexing or Email Deletion Retention policy issue? But it's just really beyond me! Both myself and a family friend who actually has IT support exp. have told him to stop using Thunderbird for Enterprise use, and migrate to a more appropriate application. But he doesn't want to have to learn anything new or complicated. Any thoughts, suggestions, other places where I can find a possible solution? One other thought: This issue does goes go away (albeit Temporary) when I clear his system cache and Force ALL Thunderbird folders to Compact. Thank you! ''If the above data is too vague, I can try to provide steps to replicate and screenshots on the next time this happens. Which is often. However, it is almost impossible to replicate on demand. '' Additionally - I've read in other forums of similar issues where they were related to indexing and IMAP syncing across multiple devices. One person commented - that it was a deletion retention failure policy within Thunderbird. Something to the effect of, Thunderbird never really deletes emails when you press delete on the desktop application. The email is marked for deletion but all of the email headers and data is still stored in the active cache, or something like that. - And apparently, there is a lag in time that the server or servers update a deletion request if the email is deleted from another app. His primary email host is Comcast.net. So, he's using Comcast Webmail, Thunderbird Desktop, and iPhone 13 mail app. via IMAP, all for the same account that has about 10+gig of stored emails. Oh, he currently has threads turned off by request. Storage cache is currently set to 650mb. Any help, suggestions or solutions are greatly appreciated. If you have any areas that need clarifying, I would be happy to take screen shots or provide additional data in order to find a valid resolution, as he's not interested in migrating to Outlook or any other Enterprise application. Thank you!