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."
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Son and daughter of murdered Chelmsford woman Maria Stubbings have been giving evidence at the inquest into her death.
Mostly dry with clear skies tonight. A chilly start tomorrow with sunshine developing.
Mostly dry with bright or sunny spells