Essex Head Coach Paul Grayson said he was delighted Mahmood had joined the club.
"I like cricketers who feel they have point to prove to people and he has lots of ability, he's experienced and he's a fit guy who can bowl with good pace as well so we feel Saj will be a real addition to the squad."
More top news
Read more of ITV Anglia's Christmas Shout Outs, passing on your seasonal messages to the special people in your lives.
Low cloud and mist developing overnight. Another mild night ahead. Generally rather cloudy tomorrow, with a few brighter breaks developing.
Generally cloudy with occasional outbreaks of rain during the morning. Some glimpses of the sun are possible. Feeling mild