As a cloud provider offering Infrastructure-as-a-Service (IaaS), we recognize the significance of outbound SMTP ports for various use cases, such as setting up email servers. However, to maintain the integrity and security of our platform, we have implemented a block on outbound SMTP ports.


This Knowledge Base article explains the reason behind this block and offers a workaround for customers requiring email transmission from their instances.

Reason behind SMTP Port Blocking

  • We have implemented a block on outbound SMTP ports due to the high volume of abuse complaints we received in the past. This block is a standard security practice among cloud providers to prevent misuse of the platform and to uphold their IP reputation.

  • Blocking SMTP ports helps to safeguard our platform and ensure the integrity of our services. By preventing unauthorized outbound SMTP traffic, we reduce the risk of our infrastructure being used for spamming or other malicious activities. This proactive approach helps to maintain a secure and reliable environment for all our customers.

Our New Virtualization Backend will offer Solution

  • We are constantly working to improve our services. In Q1 2024, we plan to release a new virtualization backend version that will allow exceptions to be configured, including unblocking SMTP ports for individual customers.

  • However, this feature will come with additional contractual agreements to ensure responsible usage and mutual protection against misuse.

Considerations for Placement on an Allow-List

  • To be considered for placement on an allow-list for SMTP port exceptions, customers will need to have a separate contract with us.

  • This contract will outline the terms of usage and ensure that customers have full control over their operational processes to prevent any potential misuse of the SMTP ports.

Workaround Until Our New Backend is Available

  • In the meantime, we recommend utilizing third-party email services such as SendGrid or Postmark. These services allow you to transmit email content through their APIs, and they handle the actual email sending process, bypassing the need for outbound SMTP ports on our platform.

  • With this workaround, you can send emails from your instances while maintaining security and compliance with our platform policies.