Usually translate5 uses the standard mail server, that is configured via php.ini, which usually goes through sendmail on Linux.
Yet it is possible to configure any mail server to use for a certain translate5 installation through smtp in translate5's installation.ini.
To do so you can use a configuration like this:
resources.mail.defaultFrom.email = email@example.com ;this is the address that is the sender of the email
resources.mail.defaultFrom.name = "Translation Company" ;this is just hte from name for the email
resources.mail.transport.type = Zend_Mail_Transport_Smtp ;this is the mail transport type for the Zend_Mail class and should stay as it is for smtp
resources.mail.transport.host = your.smtphost.com ;this should be the hostname of your smtp server, that should send the mail
resources.mail.transport.name = translate5.translationcompany.com ;this should be the domain name of the server, that runs translate5
In general you can use any kind of further configuration Zend_Mail of Zend Framework 1 allows. For a number of examples please have a look here.
To send every mail the server sends as bcc to certain addresses you can add the following lines
runtimeOptions.mail.generalBcc = firstname.lastname@example.org
runtimeOptions.mail.generalBcc = email@example.com
How to configure translate5 to only send error mails to certain addresses (or to only send errors of certain log levels) please read here.