You Do Need power plug adapter while traveling from Yemen to Mali.

Here is Why You Need An Adapter

The outlet and plug type used in Mali are C and E and in Yemen are A, D and G. This is how they look like.

Yemen

In Yemen, outlets of type A, D and G are in use.

Type A

Type D

Type G

Mali

In Mali, outlets of type C and E are in use.

Type C

Type E