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I've not used Enigmail, I didn't know it was that bad. I use Claws-Mail myself, which has an included by default gpg plugin.
One of the reasons keyservers are used are so people can get someones public key BEFORE they contact them securely, and don't have to wait for someone to send them their public key block before they check a signature. For example, if I sign this comment, you could grab my pubkey from Slashdot and/or the keyservers to check the sig and not have to send me an e-mail or reply to this comment asking for my pubkey. Though if I want the sig to get past the lameness filter I have to use SHA1, not SHA256 (which requires a quick config edit)
That said, while claws-mail does have a "Insert My Public Key Block" function in the Tools menu of the compose window, it can't as far as I know, automatically attach a pubkey. And if it did, people would probably complain and say things like "Why do I get these weird text attachments from claws-mail users all the time"
But you're right that it isn't Mom-proof, though it's better than it was.
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