only in my laptop , during the boot, it always stops for about 35 seconds with exim4:

I'd like to know if i can stop this MTA daemon without problems to other services in Linux.

yes

most distros use sys V bootup scripts so with root powers go to
eg
/etc/rc5.d or look at your /etc/inittab to see what the default run level is

and disable the daemon

2) if you need more help pls name your distro

3) you can manually start your mta at boot....or if the mta was looking for something you can make it start last in your /etc/rc.local

4) However, it is more likely you have some config issue.
I like postfix others swear by sendmail so if not sure can you at least say if you need
local mail only or you need external sending and/or receiving

5) Your firewall may also be interfering and not your mail configs so name your firewall pls and if you have a router firewall

yes you should be able to skip it, if you want you can fire it up at the end in the background (like run the init script out of rc.local)

I use Debian (Lenny).
I removed the exim4 pakage with apt-get remove --purge. By the way, it is not important now. I was afraid doing that it could provoke some kind of problems to other services.
Like i could see, people prefer most postfix. Then, when I need a MTA i'll use the latter one.

Tnx.

Another solution which works in Debian is to modify /etc/hostname so it has a qualified name. For example, you could change this:

booberry

to this:

booberry.gonzo

My prefered solution, though, is to not install exim4 in the first place. I like to start with a minimal install (not even the so-called "base" suite selected), and only install what I want. I don't know what depends on exim4, but so far I haven't ever installed anything that requires it.