I am starting to plan my upgrade from Thunderbird 52.9.1 to 115. 115 seems a little immature at present, so I'll be waiting until the new year before I do the upgrade but there are a lot of issues so I'll need the time to deal with those anyway. I have 11 email accounts. Half of those have S/MIME certificates which I get from actalis.it. They are free and have to be renewed each year. Each year a new certificate is created and imported in to Thunderbird. I use an add on called "security settings from address book" which allows me to automatically encrypt emails to recipients who have a flag set in the custom fields. This addon is not supported in Thunderbird 115, but I'm hoping the new certificate functions in 115 will work. I will not be using OpenPGP, Enigmail or GNUPG. As each email address gets a new certificate each year I have to import each certificate to be able to access these older emails. So my question is this; I assume if I don't import the certificates for each account for every year I will be unable to access the emails that were sent/received during the valid period of the related certificates - is that correct? How will this affect people with whom I sent/received encrypted emails? Are they going to have to upgrade to 115 at the same time? I would have thought that as long as they have their certificates already installed in the same manner in which I had in my old Thunderbird they would not have to do anything? Unrelated to encryption/digital signatures, I've just had a thought... Am I going to come across any issues pointing Thunderbird 115 to my existing mail folders? I believe there is no "upgrade path". I have to do all of this from scratch? I have about a 1,000 filters. Everything gets moved out of the inbox for the account into one or more folders on the Local Folders, where all of my mail folders reside. Can I copy the msgfilters.dat file for each account to the new installation and it will work? Or am I going to have to create all of the filters from scratch too? thanks.