We have compiled some suggestions to keep in mind when sending DMs to minimize being flagged as spam. Since Instagram is constantly being abused by spammers and bots we highly recommend that you take extra measures to avoid being grouped together with these.
Be patient after sending DMs. Don't send too many in a short period of time.
Add a personal touch to each message (e.g. greeting with name)
Don't send all DMs at the same time. Instead, spread them out throughout the day
Change your request message template frequently
Try to vary your DM by writing them manually frequently (remember to include the link when sending rights requests)