Update settings for earthlink.net

[cketti]

Updating this because a K-9 Mail user reported an Earthlink related issue that made me realize automatic setup didn't work for them. That's because K-9 Mail ignores entries not using any transport encryption.

I changed the authentication method for the outgoing server to password-cleartext because the server only announces support for PLAIN and LOGIN.

> EHLO autoconfig.test
< 250-hello TLS
< 250-AUTH LOGIN PLAIN
< 250-8BITMIME
< 250-PIPELINING
< 250-HELP
< 250-CHUNKING
< 250-BINARYMIME
< 250 SIZE 52428800

Earthlink documentation: https://help.earthlink.net/portal/en/kb/articles/email-server-settings

[babolivier]

Looks good to me, documentation matches with settings