Time limit for posting notice of EGM

Suppose a board meeting was held today i.e. 24.02.2014 and an EGM was called on 24.03.2014 (28 days from EGM). The notice of EGM was signed on 24.02.2014 but due to some reasons, the notice could be posted by speed post to the shareholders on 01.03.2014 (23 days from EGM). Will the notice be valid, keeping in mind 21 clear days notice is required?

Please also tell, what if the company manages to dispatch the speed post on 28.02.2014?