mail-app not showing some highlighted parts of messages

The Basics

  • Nextcloud Server version (e.g., 29.x.x):
    • 33.0.5
  • Operating system and version (e.g., Ubuntu 24.04):
    • Slackware15.0 x86_64 (post 15.0 -current)
  • Installation method (e.g. AlO, NCP, Bare Metal/Archive, etc.)
    • Docker- nextcloud:33.0.5

Summary of the issue you are facing:

Nextcloud mail-app does not show some parts messages (e.g. from Udemy).

Here the image using mail-app on nextcloud:

Here the same e-mail on GMail using web browser:

Steps to replicate it (hint: details matter!):

  1. Logging on Udemy

  2. It sends an e-mail message with a 6 number’s code for authentication.

  3. Open message on Nextcloud Mail and doesn’t show the code.

Log entries

Here the parts with code in the mail message:

diniz@darkstar:~/Downloads$ grep -C 5 -n 901974 udemy_mail.eml
93-
94-Ol=E1, Diniz,
95-
96-Use o c=F3digo abaixo para fazer login na sua conta da Udemy.
97-
98:901974Este c=F3digo expira em 15 minutos.N=E3o solicitou o c=F3digo? Fale c=
99-onosco.
100-
101------------------------------
102-Entregue por Udemy 600 Harrison Street, 3rd Floor, San Francisco, CA 94107.
103---a61c63a318f931545f6281408626a4872c864e61d4ef87e4a4f2f13dff93
--
202- =20
203- <p style=3D"margin-bottom:0">
204- <a href=3D"" style=3D"text-=
205-decoration:none; color:#1C1D1F"><h1 style=3D"background-color: #d3d3d352;te=
206-xt-align: center;"><a href=3D"" style=3D"text-decoration:none; color:#1C1D1=
207:F">901974</a></h1></a><a href=3D"" style=3D"text-decoration:none; color:#1C=
208-1D1F"><p><a href=3D"" style=3D"text-decoration:none; color:#1C1D1F">Este c=
209-=F3digo expira em 15 minutos.</a></p></a><a href=3D"" style=3D"text-decorat=
210-ion:none; color:#1C1D1F"><p><a href=3D"" style=3D"text-decoration:none; col=
211-or:#1C1D1F">N=E3o solicitou o c=F3digo? </a><a href=3D"https://e2.udemymail=
212-.com/ls/click?upn=3Du001.9GWSZeWdmdf6rKBC5BsLZ2XRgp4nWQUKH3JsjxFFsFm-2BZGzC=

Below link to complete message on termbin.com:
udemy_mail.eml