SMTP error "451 4.7.1 Please try again later"

If the DEFENDO mail server keeps rejecting emails with the message "451 4.7.1 Please try again later", it is usually caused by either the mail virusscan module or the MIME filter. It is often sufficient to stop and then start service "Mail server" in DEFENDO menu "System > Services" on tab "Server".
If this solved the problem for the moment, but the same situation reappears after a while, it could be caused by memory shortage.
Please contact technical support if the problem persists.

Secure

DEFENDO forces a collection of best-of-breed security modules like firewall, VPN, proxies, virus scanner and anti spam system to interact for one purpose:
To be protected from all online threats and unwanted contents like malicious code, spam and hacker attacks.

Flexible

Each IT scenario is different. The DEFENDO product family will adapt precisely to your demands.
DEFENDO applies for simple Internet connections of small companies, for headquarters / branch office WANs, as well as for complex multi-tiered firewall systems.

More good reasons

  • No backdoors
  • More than 20 years of Internet security experience
  • Award-winning product
  • Support by our development engineers
  • Reseller loyalty
  • Made in Germany