Since a few weeks I use a S/MIME Certificate with my posteo.de Account. I bought the certificate through posteo. see their blog.
I installed the certificate in Thunderbird (works well) and AquaMail Pro 1.51.1-461 on a Pixel 6a (Android 14, latest update).
First it worked to sign emails on Thunderbird and Aquamail, but recently my signed Emails are rejected by the Posteo-SMTP with following message:
521 5.5.2 submission01.posteo.de Error: bare<LF>received
Posteo support tells me that the signed messages are not properly formated and they reject for security reasons.
What can be done to solve this issue?
