Cold email for SaaS gets harder once you start scaling

Cold email was pretty simple when I was only running a small campaign a couple of inboxes, a small list and not much to manage.

Once you start increasing the volume, it gets a lot more complicated. More inboxes, more domains, deliverability, DNS and keeping track of what's actually working.

The annoying part is that all of this is separate from the actual marketing. I would rather spend my time finding better prospects and improving the campaign than constantly managing email infrastructure.

I've seen people handle this completely differently too some keep outbound separate from their main company email, while others seem to run everything together.

I'm trying to figure out what actually makes sense once a SaaS campaign starts getting bigger without creating a bunch of unnecessary work.

For anyone who's already scaled SaaS outbound, what ended up being the biggest headache?