The ornamental design for an all weathermailboxopeningindicator, as shown and described.
FIG. 1 is a front top right perspective view of an all weather mailbox opening indicator with a closed mailbox shown in broken lines to show the environment forming no part of the claimed design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a right side elevation view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a back elevation view thereof;
FIG. 7 is a left side elevation view thereof;
FIG. 8 is a front top right perspective view of an all weather mailbox opening indicator with an open mailbox shown in broken lines to show the environment forming no part of the claimed design;