Question

I’m looking to use Javamail in a situation in which many emails will be sent from many users using their respective SMTP servers. (Yes, it resembles a spam framework, but it is a legitimate business product). I’m wondering if Javamail supports this situation as it looks like I will have to create a separate session for each user. So my questions are:

1. Am I correct in that there will be one Javamail session needed per user?
2. Are sessions light enough to create and clean as they will be ephemeral per user in my application?
3. Does this design work or will javamail horribly break down under load, a situation in which many sessions are checked out, etc.?
4. If “yes” to 3, is there an obvious library I should be using instead that works better in this situation?

Answer 1

1. Yes, it would be easiest to use one session per user.
2. Sessions
   contain mostly just configuration information, so they’re lighter weight
   than a connection, for instance.
3. It depends a lot on your environment and your performance requirements.
4. If you find that creating a Session per user is too expensive, you can use a single Session and manage the Transport objects yourself, setting the configuration you’ll need on each SMTPTransport object. The primary cost in either case is likely to be the connections (represented by the Transport objects). You may need to limit the number of connections active at any time.