Hello,

Most mail clients are extremely similar. The comparison would say that every client is effectively the same, with some differences here and there.

Also good to note that although originally made by Mozilla, Thunderbird is no longer funded by Mozilla, and there is a community keeping it up-to-date.

Thunderbird is one of the only free (as in cost) and Free (as in freedom) email clients.

I personally would recommend Thunderbird for these reasons. It is effectively the same as all other clients, but respects both your wallet and your freedom. It also is maintained by the community, meaning features wanted can be added easily.

I understand. Still, a side-by-side comparison would make sense even if many things are the same. Consumers like to see things compared specifically to something else. This is how they determine what's "better." Firefox was compared to Edge Browser, even though according to the checkbox visual, they were mostly eye-to-eye.

I can not see anyone in the community being interested in performing such a side by side process.

Intrinsically email is a lowest common denominator product. New feature are largely pointless as other mail readers do not render such things. This is such an issue that the professionals in the space like campaign monitor offer detailed instructions on what is and is not supported across readers. https://www.campaignmonitor.com/dev-resources/guides/coding-html-emails/

There is a fairly good comparison on Wikipedia, and as it is a not for profit probably is the least biased source. https://en.wikipedia.org/wiki/Comparison_of_email_clients#Features