[Thomas12400]

We should maintain Husn Zann (positive viewpoint) with the Ulama and Shaykhs.

Usually there's not much need to mail Ulama all around the world, i believe. If one has got a query related to Fiqh, he can ask a local qualified Mufti. If he has got some Islah related query, then he will have to form a Islahi relationship with a Shaykh to acquire the complete benefit (i.e. asking him on a few occasions and doing at other times according to one's own nafs according to some other Shaykh wont help much). The Shaykhs usually respond to the Islahi letters as soon as possible.

As far as the question of OP goes, then it seems correct that not Ulama are "deficiency less", neither all have similar preferences and routines. So its possible that few of them tend to reply to emails quicker than others. Secondly, i think that many Ulama are not well versed with computers and similar stuff, themselves. This creates a barrier between them and their email messages/queries. Wallahu A'lam