The Saracens winger, 28, was cited for making contact with the eyes of Ulster's Luke Marshall in a European Champions Cup game.
The suspension came just a week after he was recalled to the England squad, 18 months after his last appearance.
Ashton pleaded not guilty at a hearing on 20 January and is appealing against the level of the sanction.
He received the full written decision of the independent disciplinary hearing judicial officer on Friday, 22 January.
England begin their Six Nations campaign in Scotland on 6 February and end it on 19 March in France, with Ashton's ban finishing on 28 March.
Head coach Eddie Jones said he would wait for the outcome of any appeal before naming a replacement.
However, Bath wing Semesa Rokoduguni has been called up as cover and the 28-year-old will join up with the England squad until a final decision is made on Ashton's case.
Chris Ashton will appeal against a 10-week ban that would rule him out of England's entire Six Nations campaign.