For what it's worth, I like the proposal, in large part because it is a rewrite with an aim to implement a full-featured cross-platform mail client. Something

For what it's worth, I like the proposal, in large part because it is a rewrite with an aim to implement a full-featured cross-platform mail client. Something fresh but with the spirit of Thunderbird and consistent with the Mozilla credo appeals to me. But to answer your question, I and several others I know whom use Thunderbird consider it a "least awful" choice. It's less complicated, opinionated, and buggy that Outlook. It's cross-platform unlike some of the other top-tier options. And it's less centralized, surveilled, and inverse-productized than third-party web-based email such as Gmail. It supports multiple accounts, through add-ons it supports GPG, it blocks bad HTML in messages, and for the most part it works well enough. However, yes, I do have a lot of problems with Thunrderbird, ranging from daily annoyances to minor pet peeves. Reviewing my Bugzilla votes would be exhausting, but some highlights: As others have pointed out, the search functionality is poor. It's slower than alternative clients (e.g., Opera Mail) and less accurate. It also opens to a low-value "search results" view rather than a list view. ( See https://bugzilla.mozilla.org/show_bug.cgi?id=580252 https://bugzilla.mozilla.org/show_bug.cgi?id=580252 ) It's not easy to quickly execute a search on the current folder only. The full search is so frustrating that I am in the habit of using the quick-filter bar (control-shift-K) because it works as I feel an e-mail search should work, but woe to the user who has "Body" selected in that UI control since the filter function does not use the search index. Also, why does ESC hide the quick-filter bar? Addressing is slow even on extremely fast workstations, to the point of routinely causing me to need to correct addressing errors. However, they recently fixed bug 1012397 so that resolution will occur after a blur of an addressing field. Yay! ( See https://bugzilla.mozilla.org/show_bug.cgi?id=1012397 https://bugzilla.mozilla.org/show_bug.cgi?id=1012397 ) Though other composition / addressing quirks such an improper initial focus on the composition pane still remain. ( See https://bugzilla.mozilla.org/show_bug.cgi?id=329482 https://bugzilla.mozilla.org/show_bug.cgi?id=329482 ) The email composition window is often slowed by activity occurring elsewhere within Thunderbird. If Thunderbird is working on moving a bunch of messages, for example, it can sometimes struggle to keep pace with typing in a composition window, on workstations with 8 or 16 modern CPU cores and NVMe SSDs. All told, I would also be more or less happy with ongoing improvement to the existing product. But I understand that may not be viable if the underlying technologies start fading away.