UNDELIVERED MAILS

Question

For the past 2 days my mails are immediately undelivered with the following message:

le 16/06/2026 15:29

521 5.7.1 Client host rejected by spamhaus for spamming issues; please refer to Listed by XBL, see https://check.spamhaus.org/query/ip/77.141.38.3 for further information

Bonfire9911 · Answer

Typically with consumer ISPs, when you reboot the router you'll get a different IP, but that didn't happen for you. Did you see an IPv6 address underneath the IPv4 address on the whatsmyip site⁉️

I would try the following (unless you want to contact your ISP):

* Shut off the router for several minutes, then power it back on and repeat the steps above — maybe do this during a break or while you sleep.
* Send emails from a web interface (if available) for now.
* Contact your ISP and ask how your router gets assigned an IP on reboot and what you can do to get a different IPv4 address.

Longer-term, move toward IPv6 if your ISP and email provider support it, because being listed on a spam list due to other customers is less likely with IPv6. Your IPv4 address is most likely shared with other ISP customers. However, If you already see an IPv6 address on the whatsmyip site, you already have IPv6 enabled; in that case talk to your email provider about their blocking your IP and not using IPv6.

JA43 · Answer

Thanks for your advice, I switched off the box and after 30 seconds switched it on, the IPv4 is still 77.141.38.3. and the mail i tried to send has been immediately undelivered.

What could I do next?

Thanks

Bonfire9911 · Answer

Your current IP address appears to be on a spam list. You can verify this by using the site whatismyip to check your IPv4 address and see if it matches 77.141.38.3.

The usual method of rebooting your ISP router may work: turn it off, wait 10 seconds, then turn it back on. Then check the site above again to see if you get a different IP address, and try sending the emails again.