I'd like to achieve the following:
- Be able to aggregate my email accounts such that I can receive an email sent to one of my email accounts and reply to it from any other email account of mine, without having to switch email clients, and without breaking conversation threading.
- Be able to send signed and/or encrypted emails using either PGP/GPG or S/MIME from any email client I use.
- Be able to access my emails securely on my computer (e.g. via a Web-based email client using HTTPS, or via an email client program installed in an encrypted partition on my computer).
- Be able to access my emails securely on other people's computers (e.g. via a Web-based email client using HTTPS, or via an email client program carried on an encrypted USB key).
- Be able to access my emails securely on an Android mobile phone, using an email client that allows me to read and write messages when not connected to the internet.
- Be able to search on the subject, message, sender, to, cc and bcc fields of my emails from any email client I use.
- Be able to a graphical email client in all cases.
Currently, Gmail partially provides 1 (only via the Gmail interface on the Web: not via mobile or via local clients, AFAIK), and fully provides 3, 4, 5, 6 and 7. It may also be able to partially provide 2 (again, only via the Gmail interface on the Web, and only when using Firefox to access it) with the addition of the Gmail S/MIME Firefox add-on, but it's possible this would impact on 6.
Is there a solution that fully provides all seven? It needn't be based on Gmail. If so, what is it?
By a "solution", I mean some combination of:
- email host,
- email client to use on my my computer,
- email client to use when the only internet-connected device available is someone else's laptop/desktop,
- email client to use on Android,
- and any configuration details that might be necessary.