im developing a website which sends alot of emails (registration, forgot password, transaction, etc..) and currently i'm using PHPMailer and gmail's SMTP to send them. They work pretty good and i never had a lost email.

So what is wrong?

Well, since it has to login to the SMTP and such it takes longer to load the page. For example when a user makes a transaction it takes about 900-1000ms longer to finish the request. I balieve that sending emails like this is a very bad idea.

What to do?

I never had to send mails this way so i dont know which is the fastest practise.

I was thinking to write a little python or php cli service which has a queue with emails to send. When an email must get delivered it will take care of it.

Not sure if this is perfect. An suggestions?

I believe that sending emails like this is a very bad idea.

You are correct.

Any suggestions?

Sending mails (or any process that takes a bit of time for that matter) should always be done in the background, so the frontend stays fast.

You have different ways of doing that:

• Insert/flag some row in the database, and have a cron job regularly check if there are such rows to be processed. This is simple enough to implement and works well if delay is not a problem. If you need to run the cron too frequently though, then move on to the next solution.
• Using a third-party queue/messaging service like RabbitMQ. This is a bit longer to setup, but it's a very solid and versatile architecture: the frontend sends whatever tasks you want to the service, which takes care of queuing and distributing them to your workers scripts. Can be used for sending your emails, resizing images, generating PDF, etc. Whatever takes time can be moved in the background.

Now there is another solution that works for emails in particular, if you have some system administration skills: use a SMTP relay.

• Instead of querying Gmail SMTP directly (which is slow), your frontend delivers the mails locally (which is fast), and your local mail server (Postfix for example) will take care of forwarding them to Gmail's SMTP.