Organiser app with yearly reminders with attachments

[Android Central Question]

I am looking for an app/program to solve a problem that we have in our development organisation. Every year we have to do more or less the same tasks and send about the same mails and documents at specific times of the year. What we do until now is make one big document for every function with its specific tasks. However this is not very efficient as our members look at it in the beginning of the year and forget things during the year.

Every year we make up our calendar with the big events on specific dates. What I would like to have is the following:
1. An app that sends reminder emails with tasks relative to the dates (for example lecture night on 30th of october --> remind to look for speakers on the 1st of september, so 2 months on beforehand)
2. In these reminder emails an attachment with the relevant documents or old mails (most of the times the mails that have to be sent are very similar).
3. A sort of check box in the reminder mails to mark that it is done and if it is not checked that it sends a second mail after a set time.
4. An easy interface to create all these reminders.

Is there an app like this? I tried Trello and google keep, but none of them match all these specifications.

Thanks!

 

[Rukbat]

For a whole organization? There's no such app that I know of, but hiring an Android developer on contract to develop the app for you probably isn't an expenditure that will be that bad for an organization. (If the organization is an Android development organization, develop it. The calendar is there, emailing with an attachment is there, it's just a matter of developing exactly what you want in English, then translating it to Java/Kotlin.)