• Correct setup of an email app for Android (see below).
• Correct integration of the certification authorities into the operating system
• Valid digital user certificate integrated into the operating system.

Since the standard integrated e-mail app in Google Android does not support the S/MIME method, e-mail security cannot be increased by signing or encrypting with this app.

Other S/MIME-capable e-mail apps do not support all connection protocols of the e-mail system. A limited use is possible with the app FairEmail, which supports the S/MIME procedure in the Pro version, but can only access the email system of Jade University via IMAP.

• FairEmail in the F-Droid Appstore
• FairEmail in the Google Playstore

The first step is to set up the FairEmail email app as an email client:

• Main Settings tab → Manual Setup and Account Options.
• Accounts (receive e-mail IMAP POP3) → Add (+ button) → IMAP
• Provider → User defined
  • IMAP Hostname: mail.jade-hs.de
  • Encryption: STARTTLS
  • Port number: 143
  • Username: domain login (form: ma1150@hs-woe.de)
  • Password: <your password>
  • Account name: <your email address>.
• Tap the “Verify” button.
• Add associated identity (SMTP server): enabled.
• Tap the “Save” button.
  • Associated account: <your email address> (should already be preset here).
  • Your name: <first name last name>
  • Your email address: <your email address>
  • Domain name: please empty the field
  • SMTP hostname: mail.jade-hs.de
  • Encryption: STARTTLS
  • Port number: 587
  • Username: domain login (form: ma1150@hs-woe.de)
  • Password: <your password>
  • Account name: <your email address>.
• Tap on the button “Save”.

Close the settings and check that the email app is working properly.

The second step is then to increase the email security by signing / encrypting. To unlock these functions, you must purchase the Pro version (Menu → Pro Functions).

• Settings → Card Encryption
• General
  • Sign by default: activated
• PGP
  • Use Autocrypt: deactivated

Close the settings, this completes the configuration.

• In the FairEmail App, click on the pencil icon for a new email and compose it.
• Tap on “Sign”, the “Send” dialogue opens.
  • Under Encryption, select “S/MIME sign only”.
  • Tap on “Send”, the e-mail is digitally signed and then sent.
• The communication partner sees the loop symbol as a sign of a digitally signed e-mail.

To encrypt an e-mail, you must first have the communication partner's public key. To do this, have your communication partner send you a digitally signed e-mail, for example, which is automatically added to your key ring.

• Click on the pencil icon for a new email in the FairEmail app and compose it.
• Tap on “Sign”, the “Send” dialogue opens.
  • Under Encryption, select “S/MIME sign + encrypt”.
  • Tap on “Send”, the e-mail is digitally signed, encrypted and then sent.
• The communication partner will see the lock symbol as a sign of an encrypted e-mail.