dq_ctx

A dequeue context created by mtaDequeueStart().

env_to

Optional address of a pointer to receive the memory address of the next envelope recipient address. The recipient address will not be NULL terminated. 

env_to_len

Optional address of a size_t to receive the length of the returned recipient address. A value of NULL may be passed for this argument.

item_code

An optional list of item codes. See the description section that follows for a list of item codes. The list must be terminated with an integer argument with value 0.