We've looked at using the big brand providers of email processing before
but you notice their free offerings don't include the features you want and
the paid options are too expensive for companies dipping their toes into
the water of marketing in this way.
We wanted the ability to auto schedule an email to go out a week or so
after the initial sign up and the Maian Responder does it for us. Its
configurable enough for us to set it up to use a verified, DKIM enabled,
SPF enabled, google SMTP service so we have the best hopes of getting the
mail to it's intended recipient and our potential customers aren't confused
about who is sending it, because it's coming from us, not a third party
domain sending on behalf of us.
The free service enabled us to confirm it would work for us but we then had
no hesitation in paying the low cost to help Maian develop the software
Tony B - Mobunti Limited