I have been researching regarding POSTIDENT and found out that Indian passport holders cannot use this service from Deutsche post any more. This will make online services difficult for those who live in small cities or order services online.
I have used this earlier but this was couple of years bank. I have heard from colleagues that they cannot open account on online banks because they cannot get their identity verified. Even though deutsche post says it accepts Aufenthaltstitel issued in Germany, this has been refused by Deutsche Post for POSTIDENT.
I found this link on facebook https://www.facebook.com/deutschepost/posts/1805883209423283 regarding this. Many Indian passport holder as well as some European passport holders have complained regarding this. I hope Deutsche Post comes up with a solution soon and makes life for foreigners easy in Germany.
A petition regarding this has been set up on change.org please take the time and sign it
https://www.change.org/p/bafin-postident-akzeptieren-und-genehmigen-die-identit%C3%A4t-von-ausl%C3%A4ndern-in-deutschland?recruiter=48075537&utm_source=share_petition&utm_medium=copylink&utm_campaign=share_petition&utm_term=triggered