Despite the extensive analysis of the consequences of interruptions caused by smartphone notifications, research on the effects on users has so far been sparse. Therefore, in this work we (1) explore concepts on preventing interruptions elicited by notification delay in a focus group; (2) implement a smartphone application manipulating the notification delay in three distinct ways varying in the degree of user-control; (3) evaluate all three concepts with 13 users in a four-week field trial. We thereby gather qualitative feedback in 52 semi-structured interviews, one per participant after each mode and an additional control week. The results show that through the intensive preoccupation with their notification management, users reflect critically about advantages and disadvantages of their continuous reachability. Based on the results from the focus group and field trial, we derive four design implications summarizing the users' experiences and suggestions on notification delay mechanisms.@en