Check this though; I am reluctant to sent to gmail because like-
I had been told this on freenode IRC which I found rather hilarious!
Khepra: "[...] sometimes [...] an email [...] is marked as SPAM [...]" ... this sometimes will hapen often even if you had dkim, dmarc, spf, sacrified two goats, the chicken is hanging upside down and bleeding out in the basement, and the pentagram is freshly carved underneath it, in the granite slab imported from an african war region, thus soaked with more blood.... if the recipient is gmail.
Khepra: this "sometimes" will happen ....
pj: Khepra: but did you sacrifice three goats? perhaps that extra goat would have made the difference.
Khepra: I'm fresh out of goats to try :-)