Though as Heather tweets out "PLEASE PLEASE PLEASE read the submission requirements CAREFULLY!!!" But for those who don't… "TL:DR submit MAX 20 comics pages of previously published/finished work (no scripts/pitches) in a SINGLE PDF."
Valiant Comics Open Submissions For Published Comic Book Writers
Here are those submission requirements: Portfolio reviews will run for approximately ten minutes and twenty[...]
submissions Archives
And what if you are a specialist, a cog in the wheel, while publishers like to see projects from established teams? And any won;t even look at unsolicited submissions for legal reasons.
Well, in May, Oni Press says phooey to all that and is opening its submissions to all Starting at Emerald City Comic con but[...]