Eric Moore emoore at
Wed Apr 19 20:00:15 UTC 2017

 >From: Magnus Melin <mkmelin+mozilla at>
 >Subject: Re: Likely timing of future Thunderbird Gecko builds
 >Re add-ons: we want to allow the old-style add-ons since we that's a 
 >benefit for us that being compatible with Chrome et al - but supporting
 >add-ons can't be done at all costs. If it turns out that we can't 
support the
 >old style ones that's really too bad, but it's no reason to sacrifice
 >Thunderbird core. Looking at this in a perspective, add-ons are very 
niche. We
 >only have around 10 add-ons that are are popular enough to have > 1% 
of user
 >share. Not representative to this groups for sure, but that means the 
 >vast majority of users would be happy without add-ons (lightning 

One problem with an economist's prediction is that they assume people 
make decisions rationally rather then emotionally. You're quoting 
statistics as a justification to potentially drop add-ons as a niche 
feature that may be too expensive to keep. However, I suggest we don't 
think in terms of statistics, but think in terms of why did somebody 
choose Thunderbird, and why should they be loyal to its replacement? It 
won't have the halo effect of the Mozilla name, and might be viewed as 
Thunderbird in name only (think of the many users who did not migrate 
when "Windows 10 Mail app" replaced "Windows Live Mail"). Even worse if 
there is no migration tool for the profile. So what if the majority of 
users have all of their email providers in the database, millions don't. 
Think of the bad press some popular blogger or reviewer can generate 
because of migration problems they run into.

The ability to heavily customize, the large set of add-ons , your data 
not being trapped by vendor lock in and being viewed as a safe, good 
enough choice seem to be important factors.

Rather than being willing to sacrifice support for add-ons I suggest 
trying to work with a few key add-on authors such as Paolo "Kaosmos" to 
get them to migrate their most popular add-ons to the replacement 
Thunderbird. Use it as a marketing tool and avoid the mistakes Firefox 
made in shifting to the WebExtensions API.

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