Thunderbird for Android can access contacts of your phone.

Method 1: In the "To" field, type at least two characters, then Thunderbird for Android will provide matched contacts.

Method 2: Tap the three vertical dots in the upper right corner, and then tap "Add from Contacts".

Note:

1. You need to grant Thunderbird for Android the permission to access contacts in your phone.

2. Only contacts having email address will show up.

Thanks but it's exactly my problem that neither of these 2 solutions helps me. What you described works in Gmail but not in Tb. Have I maybe made some mistakes by the installation?

1. Does "Add from Contacts" show up after you tap the three vertical dots in the upper right corner?

2. Have you granted Thunderbird for Android the permission to access contacts in your phone?

I granted Tb permission to access contacts - thanks...