Hi Hector,
I can now confirm that I have now removed the IP 5.79.73.233 from our internal Blacklist and reset the confidence of that IP accross all our towers. Please allow 1 hour propagation time for the fix to take effect.
Once the hour propagation has passed, you will no longer get issues sending emails from that IP to our customers.
Please feel free to set this thread as resolved.
Kind regards
Kevin Brosnan
Tier 2 Senior Technical Support Engineer