Open Telekom Cloud for Business Customers

Secure Mail Gateway 2021

The new Secure Mail Gateway hosted on OTC will be available for new customers from October 2021. Existing customers will be migrated until March 2022. A dedicated information for them will be send out in the next months. The main features are listed below:

Forced TLS

A forced TLS communication can be set up based on the sender and recipient domain. Mails between these domains are then mandatory TLS encrypted. (In the event of an error, mails are rejected directly or not sent if no TLS connection with the external mail server is established.)

DKIM Signature

DKIM signing of outgoing mails can be configured based on the sender's domain.


Outgoing mails are checked by two virus scanners. E-mails that contain a virus are rejected with a corresponding information and a Non Delivery Report (NDR) is sent to the sender of the mail.


All Mails are checked by the AntiSpam Engine and categorized in corresponding Spam Categories.

Good Bad Routing

If the result of the AntiSpam check shows that the e-mail in question has been assigned to a spam category, this e-mail is redirected to the Bad Gateway and only sent from there to the Internet. The mechanism protects the Good Gateways from being blacklisted (protection of reputation).

Sender Domain Check

This function protects against misuse by checking whether the sender address is a valid domain before sending an email. This means that the domain has a public MX record or at least a public A record, which assigns an IP address to the domain. Mails with sender domains that do not meet these criteria are discarded.


The administration of the login accounts for the mailing of the OTC customers can be administered via the web interface of the mail relay by the OTC support.

Further information will be available soon in the service description, user guide and from our cloud handling support team.


Do you have questions?

We answer your questions about testing, booking and use – free of charge and individually. Try it! 
Hotline: 24 hours a day, 7 days a week
0800 3304477 from Germany / 00800 33044770 from abroad

  • Communities

    The Open Telekom Cloud Community

    This is where users, developers and product owners meet to help each other, share knowledge and discuss.

    Discover now

  • Telefon

    Free expert hotline

    Our certified cloud experts provide you with personal service free of charge.

     0800 3304477 (from Germany)

    +800 33044770 (from abroad)

    24 hours a day, seven days a week

  • E-Mail

    Our customer service is available free of charge via E-Mail

    Write an E-Mail

  • AI Chat


    Our AI-powered search helps with your cloud needs.

    Register now in advance and test the new Open Telekom Cloud AI chatbot soon.

    Experience the future