Why is the exim command not visible?

Question

linux

I recently moved a project to VPS hosting and came face to face with Ubuntu 12.04. Previously, I already had experience with Linux, but that was, one might say, theory rather than practice.
In general, the problem is that it is not possible to send letters. I rummaged through various logs for a long time, found out that the host did not have a banal sendmail, which was quickly installed. As a result, letters are sent from the console every other time, in php the mail() function almost always returns false (and in the case of text\html letters - always).
I have been looking for what, where and how for a long time, but I came across such a thing as exim. I had never seen this before, but I realized that it is something that works in tandem with sendmail and does wonders for sending mail. I also found his logs, where almost all attempts to send a letter contain the entry "Message is frozen".
Googled, found this article here, where exactly my problem is. And I would have already solved all the problems myself, but suddenly the ssh console does not allow me to call either "exim" or "exim4". But at the same time, it is everywhere in the system, as evidenced by the very found logs, settings files and some links.
How can I make the console see the Exim command?

Answer 1

exim should have been removed when sendmail was installed, these are conflicting packages.
Configuration files are removed only when apt-get purge exim4-config, the package manager does not touch the logs at all. So you probably don't have exim installed.