But when it comes to sending mails via wp-mail function we would always get an error message "Sorry, Something went wrong. Please try again later." And after hours of searching on the web, we still couldn't figure out why it happened. Finally we decided to switch to SendWP, since they have a 30 days money back guarantee policy if you're not satisfied with their services. We have tried sending 50 mails everyday (about 20% failed) and the rest were successful without any issues. Even though it costs us almost twice as much as other providers, but we feel we are getting a lot more value from SendWP than the other ones. Their support team is also very responsive and helpful. If you have any questions regarding their products, please feel free to contact them.