Is your goal is to influence and change behaviour or local opinions? Is it to have local champions for your goals and get people to help recruit more support? Then supporters' networks are crucial. The most influential people for ones opinions and behaviour are family, friends, neighbours, colleagues and fellow faith-group members: everyone they see regularly, talk to and respect and/or value their opinion.
So if this fits your goal, mobilise them to attract more support and/or change their behaviour. Just like any other PostBug actions, moderation is possible if you prefer to review what people are sending. Since postcards and letters tend to be kept around the house, it can also serve as a reminder in case they wish to think about it or take action on another day.
Member-get-member campaigns focus on either attracting new members to donate or to support a campaign action (and ideally give permissions for future communications). With postcard or letters, you can set-up an PostBug action with your message and images and allow supporters to enter in the recipient addresses. The postcard or letter will then be printed and posted as normal.
Asking supporters to invite their contacts to a local event is another powerful use of PostBug, especially as postcards can serve as a visual reminder card for the event that they can put on their fridge, on a notice board, by the door or other place so they are reminded of the event. The postcard can even serve as the entry ticket for the event they bring it with them. It could also include a QR code to a registration link. The possibilities are all down to your needs and creativity.
Possibilities include street parties, rubbish cleanup days, local organising events, and much more.
Some real-world action is more likely when encouraged by known contacts. For instance recycling more, going to get vaccinated, neighbour-support activities (e.g. anti-loneliness, childcare, elderly support, crisis support, etc). Postcards and letters can help your supporters organise locally on regional or national issues.