mailer.testConnection() is blocking

[gerardnico]

Following the warning request to provide why I use Mailer.getSession

Using the library 8.12.6 on a smtp server that is down (ie no service), the below code will just block.

mailer.testConnection();

I use the code provided there

[bbottema]

Thanks for raising this. The blocking behavior of mailer.testConnection() on a normally configured mailer is intentional: the no-arg call is the synchronous default, and callers that want async behavior can use testConnection(true).

One important clarification came out of this triage though: MailerGenericBuilder.async() is intended to preconfigure the mailer so callers no longer need to pass async flags manually. That applies to both sendMail(...) and testConnection(). So this issue as reported is invalid, but the related bug is that .async() currently is not honored by the no-arg testConnection() path.

I've split that real bug out as #615.