Hi @Kevin_Lynes
There was another user with an issue connecting to Krystal SMTP, although this was a while back. It may be worth trying their suggestion however. The thread can be found here: SMTP help - Krystal Hosting
We don’t actively block connections for SMTP, so I can confirm there are no restrictions on the cloudhosting domain name.
Unfortunately I’m not able to confirm the IP address used as we use a range of IP addresses as part of the scaling setup used to run QuickFile. But the IP address shouldn’t be blocked, as I am aware of other users using Krystal for SMTP.