SendMessageNL is often the best option for a fast bulk import and email sending but users should be aware of some known limitations
- there is a fixed delay time of 20' that affects immediate sending and scheduled sending that are to be done in less than 20'. This delay is due to import process time
- temporary groups should be periodically deleted by accessing MailUp console (a temporary group has the naming convention "Automatic NN", where NN is a progressive number, and it can be deleted when sending is done)
- imported files should be periodically removed from admin console user space to avoid to be charged of exceeding user space
- message scheduling fails if another sending is planned at specified date and time (you can use GetNewsletterQueues to retrieve available time slots before calling SendMessageNL)
- method call fails if import file contains duplicated email addresses
- if the file to be imported contains more than one milion of recipients please contact us
Some of the restrictions listed above will be removed in next MailUp releases, please periodically check this page or MailUp release notes.