Technically, you can.
However not through LC Email (what is LC Email?).
This means if you want to send Cold Emails through Growably, you'll need to connect your own 3rd party SMTP Provider.
More details on how to do that here.
All emails sent through LC Email must have express permission by the recipient with a clear, explicit and provable consent.
This consent should be granted through a confirmed single or double opt-in system that clearly identifies the topic of the subscription on an online or offline form via an unmarked by default checkbox.
If we ever receive an Abuse Complaint from a recipient, we will investigate it thoroughly and if you don’t have verifiable proof that you had Consent to send in some way, shape or form, your Growably Account may be cancelled and we’ll put our angry face on 
A QUICK NOTE
We typically don’t encourage cold emailing in the first place as an effective marketing strategy for MSPs as there are MUCH better ones out there that typically work WAY better than purchasing or renting lists and cold emailing them.
Check out the Marketing Foundations Workshop in the Tribal Portal for some idea 
If after all that you still plan on doing cold-emailing, we'd highly encourage you to look at tools like Instantly.AI as they are designed from the ground up for Cold Email.
Then, once a prospect has shown interest, you can add them into Growably as they are now warm and have intent.
We'd also strongly encourage you to work with an experienced cold-email expert who deeply understands things such as burner domains, IP & domain warmup procedures etc before you start.
Never attempt to do cold-emailing yourself if you're not experienced in it, it can be very dangerous. We've seen MSPs get their primary company email domain completely blacklisted by Google for months at a time from someone inexperienced running a cold-emailing campaign (meaning they couldn't even email their own clients from their Microsoft365 tenant).
If you are going to upload a list of contacts into Growably that have already opted-in to receive into from you, then please read this FAQ page first.