We use MailChimp to send out invites to our software. Some spam tools will automatically send invite emails to spam. It still happens with most of the tools out there; if you really don't want that to happen you have to implement your own email server.
We use Yesware for marketing blasts.
We use Abacus for expense reimbursement. The only issue with them is that their website does not have the most consistent behavior, but otherwise we are very happy. They have the best OCR availability of all of the other tools out there. We have tried Expensify and Tally but they don’t compare.