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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Work will start today on the first major improvement work on the Chelmer Viaduct in Chelmsford.
A cloudy start in the Anglia region with some rain. However drier, brighter conditions will spread in from the northwest during the morning.
Cloudy overnight in the Anglia region with some rain. Becoming fine and dry on Monday.