Pabbly

Pabbly's email tool includes unlimited team members on every plan level, a rarity in the category. Automation, segmentation, and SMTP routing let you send through your preferred delivery provider while managing everything in one dashboard. It's been shipping since 2011 with steady updates.

Great for growing agencies or teams where adding seats shouldn't mean upgrading plans. The SMTP routing is valuable if you already have relationships with specialized delivery providers and want to keep them.