Certified mails

I want to know how certified mail can be read using k-9 mail. I’ve read that you need an external app but I don’t know which one

There is no standard for “certified mail” so you will need to ask the party that generated it what they used and what you need to do/use to read it.


You need to install OpenKeychain and import the public GnuPG oder PGP Keys of your respondent.

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Excuse my ignorance, why does Aquamail read all certified emails from multiple senders? Without other installation ? Thank you!

Aquamail uses S/MIME.


Thanks, I’ll follow your advice, tomorrow I’ll do some tests.

Excuse my insistence, I don’t understand how to open the .eml file that contains the certified mail message. Can you please tell me where to read to learn how to do it?

The first answer is still the most applicable here.

Not with K-9. That file is an indicator for S/MIME signed/encrypted mail.

If you want to use S/MIME, use CipherMail, Aquamail, FairEmail, Bluemail, R2Mail2, etc.pp.

If you want to use GnuPG/PGP, use K-9, FairEmail, R2Mail2, etc.pp.

If you want to use both, use FairMail, Bluemail or R2Mail2.

I already use Aquamail, but I wish I could use k9mail. Now it’s all clear. Thank you.

I would like to see K-9 Mail support S/MIME as well as GnuPG/PGP as some other apps do.

I use SeaMonkey on my Linux system. Its email and news portion is based on Thunderbird and supports both GnuPG/PGP and S/MIME. I thus assume that Thunderbird supports S/MIME as well given SeaMonkey started with their code.

I obtain certificates for each of my email addresses and can thus create and receive signed, encrypted or both messages in SeaMonkey on Linux.

I use the Gmail app at present on my Android phone, but that app does not support encrypted messages although it recognizes them.

If you add S/MIME support to K-9 I will be pleased to replace Gmail on my Android phone with an app that can work properly with S/MIME.