Hi i dont understand what im saying is the port 25 used for me to send emails and things got blocked and i cannot unblock it so i want to replace it by the SSL certificate many people did that i searched the internet how to do that but i dont know how to
Thanks if u respond to my message

Your SMTP server talk with another SMTP servers thru 25 port. If your provider block it - your sever can't send any message to internet and can't receive any message, and no matter with SSL you connect to him as client or not.

I think you must find IT specialist, who did it for you. If you can't understand this simple information - you can't do it by yourself.

What reason why your provider block 25 port for your VPS? You send spam or what?
If your mail server have blocked 25 port by your provider for some reason - I think you need find another provider or correct configure your mail server (SSL,DKIM,DMARC, SPF and etc) and ask provider about unblocking.

Is there really no way to get all mails from different accounts in one inbox and also keep them separate in own inboxes as it is e.g. in Mailspring?

Folder structure looks like this (BTW- You should enable posting screenshots in your forum)

INBOX (with all mails from all accounts)
-- mailbox (1st address)
-- mailbox (2nd address)
-- mailbox (3rd address)
and so on

Is there maybe a plugin that can add this functionality?

As mainspring has to be installed on each PC I want to have a server for this to make all mails accessible in browser.

I have to check about 50 inboxes, so IF NOT - roundcube is the wrong choice.

Any tips which app running on a Linux server – accessible in browser can do what I need?

Breadcrumb #2:

Postgres setup:

From the postgres account, and with Postgres already up and running acceptably:

As your Round Cube user will be a "virtual" user - that is, without an OS level account - you then create a database and user, then grant privileges and so forth and confirm access. The username and database name are arbitrary, however I simply chose 'roundcube' - wherever you see that you can change it here:

   $ cd ~/data
   Edit pg_hba.conf to:
      modify the default line reading 'local all all peer' to read 'local all postgres peer' (note a single space is enough).
      add a line reading: 'local all all md5' - what this does is KEEP Postgres from having to provide a password while all other users do.
   $ pg_ctl reload
   $ psql
   postgres=# create database roundcube;
   postgres=# create user roundcube;
   postgres=# \password roundcube
   <respond to prompts>
   postgres=# grant all on database roundcube to roundcube;
   postgres=# \q
   $ psql roundcube
   roundcube=# grant all on schema public to roundcube;
   roundcube=# \q
   $ psql -U roundcube
   <respond to password prompts>
   roundcube=# \q

Then, as root:

   Add (or edit) an entry in /etc/roundcubemail/config.inc.php so you have this line:

   $config['enable_installer'] = true;

   Then, apply a URL sort of like this:

      https://<domain>/mail/installer

   And observe! Walk the steps to get to telling it to initialize the database.

Then, as postgres:

   psql -U roundcube
   roundcube=# \dt
   ... and look at all the nice tables that have been created!

...From here you already know how to exit psql and from here all that's left is your SMTP configuration and IMAP testing.

       

how exactly should I create it?

I do this sort of thing with a combination of SpamAssassin and ProcMail (which wasn't supported for a few years but now is supported once again).

SpamAssassin looks at all inbound email and ranks them for whether or not they're spam and you can add rules that indicate to SA that it's not wanted. And then ProcMail moves it to the user's SPAM folder or just deletes it, etc. That can be done in several ways but I like (non-virtual) users to have control via their ~/.procmailrc file.

In fact, the user can do it all with ProcMail, without Spam Assassin, I think. For example, in my own ~/.procmailrc file I have (the --- lines denote start and end of an excerpt):

---
:0
* ^From:.*northlightcolor.com
spam

---

...Of course, this is done at the SMTP / MTA level as in my config, Postfix calls SpamAssassin and ProcMail...