Hey there, I'll give you a very simple, short solution to this at present. If you just check where your target audience lies.
If these are bigger enterprise companies, go and set up a good infra. on Outlook mailboxes. If these are smaller startups or small SMBs, go and set up your entire infrastructure on Google mailboxes.
Don't worry much on warm up tools at present, just use any. I prefer Smartlead.
For google malboxes we can help: theboomerang.co ( $1.8-$2.25/mailbox)
