===== Identification of e-mails in the subject line =====

All e-mails sent via the TrutzBox are automatically encrypted by the TrutzBox. If the recipient is a TrutzBox (and thus the mail address ends with @comidio.email), then the TrutzBox automatically obtains the required public key of the recipient. If the recipient does not have a TrutzBox (and therefore a normal e-mail address has been addressed), the TrutzBox administrator must first inform the TrutzBox of the public key of the recipient. For security reasons, it is not possible to send an e-mail to a recipient if the recipient's public key is unknown.<br/>

All encrypted e-mails received by the TrutzBox are automatically decrypted by the TrutzBox and made available for retrieval of an e-mail program. The TrutzBox can also receive e-mails from normal e-mail servers. These can be either encrypted or unencrypted. To show the recipient of the e-mail whether the e-mail was encrypted or unencrypted and whether the TrutzBox was able to check the sender's signature, the TrutzBox adjusts the mail subject field in the e-mail.<br/>The TrutzBox places text in square brackets before the mail subject as <u>first the letter </u>

*U - for unsigned (the TrutzBox could not confirm the sender), or