As you know, versions of Postbox compatible with SpamSieve are 32-bit and will not work with MacOS 15. If I like and use many of the archiving and search features in Postbox 5.X, which of the still-to-be compatible clients should I check out as a replacement?
I think Apple Mail and MailMate probably offer the most similar features.
Apple Mail is extraordinarily improved since I chose Postbox/Thunderbird over it many years ago. I does now have all of the features I need, and if it performs adequately with the very large corpus of archived e-mails I like to keep indexed and handy, that will be my choice. Text (including Markup)-only in MailMate is too heavy a lift for me.
That’s great to hear. I also have an app that some people use to keep their large e-mail archive separately from Apple Mail (and other clients). This provides more flexibility to choose an e-mail client they like for reading/organizing/composing, without also requiring it to handle large amounts of old mail efficiently and reliably.
Yes, I should learn how to use my copy of Eaglefiler to do this. (I bought it to use for this purpose before I figured out how to do it in Postbox (and now in Apple Mail), but haven’t used it.) By far the best application in its class!