Technically you can, however we recommend you don't - see below for why.
Currently, Growably can only be configured to authenticate DKIM for a single Domain / Sub-Domain.
This means that whilst you technically can send emails from multiple Domains / Sub-Domains using Growably, some of those emails will fail DKIM Alignment which leads to email deliverability issues.
(your emails won't land in your recipients Inboxes)
The only emails that won't fail DKIM alignment are ones that are being sent with the specific Domain / Sub-Domain that you have setup in your Mailgun / Email Integration.
In the coming few months (as of February 2024) this will hopefully change as High-Level has recently made some changes to the email sending side of the platform.
However we're not sure when those updates will be available in Growably.
In the meantime, we recommend you only send emails from a single Domain / Sub-Domain.
If you're not sure what Domain / Sub-Domain you should send from, check out this FAQ Article.