MailQ is a module that queues ALL mails originating from a Drupal site into a queue and then processes this queue and sends mails in batches during cron runs. However, it still uses drupal core or other modules like Mimemail to actually send the mails.
Update: A new release 6.x-2.0-alpha1 is now available. Download and try.
This means that one can use mimemail AND MailQ togather. MailQ will "queue" the mail to a table, and then during cron runs send emails in batch.
MailQ is especially useful on sites that are run on shared hosting servers that have limits on the number of emails that can be sent per hour. MailQ will smoothen out spikes in the number of emails sent per hour by queuing mails and then sending them later during cron runs in batches whose sizes are totally within your control.
MailQ includes the following features:
- Set a batch size to run
- Set a "max try" value so that if a mail fails to send once, the mail will be retried.
- Select the "mail library" that you wish to use to send mail, or you can decide to ONLY queue mail, which is good for development. You could e.g. select from mimemail, smtp mail, or the drupal default mailer.
- Debug mode to see exactly what is happening.