Generally, it's best not to go to overboard with the length of time between batches; I would generally recommend never going over 5 or 10 minutes. I would also recommend not having a batch of more than 1,000 messages. If these limits don't seem reasonable, it's best to lessen the time between batches (from 5 minutes, to 4), instead of having more messages per batch.
Mojo Mail is primarily run as a plain old CGI script, it does not need any special modules installed, except the one it comes with. It does not run as a mod_perl enabled script and needs no special treatment. If you can run CGI scripts on your hosting account, Mojo Mail will work for you.
When submitted, Mojo Mail will take the request and email a confirmation. This email confirmation will include a special URL that includes a special 'pin' number, which is used to confirm the correct person wants to subscribe. Following this link will subscribe the email address.
Unsubscription is a similar process, where someone who wants to unsubscribe will fill out a web form with their email address and receive a confirmation email.
Mojo Mail does not support email confirmation. That is, confirming an address by having to replying to an email. The URL confirmation is usually much simpler and doesn't make you create an alias email that goes to a program that does the confirmation. We circumvent quite a bit of complexity this way.
Mojo Mail can be configured to do these two simple things in a variety of ways. Mojo Mail also takes account of if the email is already subscribed to the list, if the email is 'blacklisted' and thus unable to subscribe, invalid emails, and a plethora of 'gotchas' when dealing with these things.
Message sending can also be done in 'batches' a desired amount of emails are sent in timed intervals.
Mojo Mail saves its information in many different files, in two formats, plain text and DB_File.
The list subscription list is saved in a plain text file, with one email per line. The file is called 'list_name.list' where 'list_name' is the name of your list, with underscores instead of spaces. Blacklists are stored in a similar way, but with a 'blacklist' extension.
DB_Files are used to saved list information and to archive messages. Mojo Mail is flexible in what DB_File package you use, be it DB_File, GDBM, ODBM, or SDBM
list information is stored with one preference per key, archived messages are saved with the date sent as the key, looking like: 20010308151009 (YYYYMMDDHHMMSS) with the value being the subject, the message and then the message format, delimited by double colons '::'