Denver Broncos safety Kareem Jackson returned from a two-game suspension, only to be suspended again on Monday for repeated violations of player safety rules after an incident in Sunday’s 21-20 win over the Minnesota Vikings.The NFL announced that Jackson is suspended four games without pay for his hit on Vikings quarterback Joshua Dobbs. NFL vice president of football operations Jon Runyan issued the suspension and detailed the violation in a letter to Jackson, who had just served the two-game suspension that had been reduced from four upon appeal.”With 13:38 remaining in the first quarter, you were involved in a play that the League considers a serious violation of the playing rules,” Runyan wrote in the letter. “The video of the play shows that you lowered your head and made forcible contact to Vikings quarterback Josh Dobbs. You had an unobstructed path to your opponent and the illegal contact could have been avoided.”Illegal acts that are flagrant and jeopardize the safety of players will not be tolerated. The League will continue to stress enforcement of the rules that prohibit using your helmet to make forcible contact with your opponent. On the play in question, you lowered your head and delivered a forceful blow to the shoulder and head/neck area of an opponent when you had time and space to avoid such contact. You could have made contact with your opponent within the rules, yet you chose not to.”Jackson was not penalized on the play. He will appeal his latest suspension, ESPN reported Monday night. He is otherwise eligible to return to the active roster after the Week 15 game against the Detroit Lions on Dec. 17.Jackson was ejected for the second time this season after hitting Green Bay Packers tight end Luke Musgrave on the sideline in Denver’s 19-17 victory on Oct. 22. He missed an Oct. 29 home victory over the Kansas City Chiefs and a Nov. 13 win at the Buffalo Bills. In between, Denver had a bye in Week 9.