Zertificon Email Policy


In order to ensure hassle-free email communication with Zertificon, please read the following information.

Icon signed and encrypted email

Sender domains, encryption and signature

Zertificon exclusively sends emails from the domain zertificon.com or related subdomains.

All emails are signed by default. When you receive an email from Zertificon, please verify its signature to ensure the email was actually sent by Zertificon.

In addition to that all emails are encrypted using S/MIME or OpenPGP, if possible. Please ensure that your certificate is publicly available. Otherwise please send us an email signed with your certificate.

If you do not own an S/MIME certificate or an OpenPGP key, but still wish to communicate with us confidentially, please inform your contact person at Zertificon. They will see to it that a Z1 Messenger account is set up for you.

You can find our email encryption certificates and publish your own at our certificate search engine Z1 Global TrustPoint.

Direct links to our company certificates:

S/MIME (*.pem)
OpenPGP (*.asc)

Icon email attachments

Email attachments

For security purposes all attachments from incoming emails that could potentially contain dangerous content (viruses etc.) will be blocked. These attachments are then removed from the email traffic. Sender and recipient will be notified about this process.

Whenever possible please convert your documents to PDF before sending them.

We accept the following file formats:

  • ai
  • asc
  • bz2
  • cer
  • crt
  • der
  • eps
  • gpg
  • gz
  • jpg
  • log
  • p7b
  • p7m
  • p7s
  • pdf
  • pem
  • pgp
  • png
  • rar
  • tar
  • tar.gz
  • tgz
  • txt
  • zip

Files which may contain other file types such as zip archives or PDFs with attachments will only be accepted if all contained file types are also accepted. Example: A zip archive will be blocked if it includes a docx file.


Icon size limit for emails

Size limit

The total size of an incoming email must not exceed 30 MB. Larger emails will be rejected by our server; the sender will be noticed.

To securely transfer large files please ask your contact person at Zertificon for an upload link to our Z1 SecureHub.

Icon virus and spam filters

Virus and Spam filters

Zertificon is using virus and spam filters. Any emails classified as unwelcome by these filters will not reach their recipient and for security purposes neither sender nor recipient will be notified.

If only the attachments of an email are classified as potentially dangerous, the attachments will be removed and the email is forwarded to its recipient with a notification.