Problems with subject encoding

[mrgreiner]

Hi,
I'm having trouble with the encoding of the subject with some emails. Using the Webclient, as an example, instead of something like:

Re: Parcelas Abertas:

I'm getting the following:

=?ISO-8859-1?Q?Parcelas Abertas: ?=

The same email, downloaded using POP3, in Thunderbird, does display properly. Could somebody point me how I could correct this?

I'm using ZCS 8.7.11_GA_3822 (latest patch for 8.7), in a Centos 6.10 VM, virtualized using Citrix Xen.
The VM has 600GB disk space, 4 CPUs and 8GB RAM.

Thanks,

Roberto