Why I switched from Mandrill to Mailgun for PrestaShop

I was working on an override of PrestaShop's "forgotten password" feature (article to arrive here shortly) when I ran into a problem... the "forgotten password" email that I was sending to my Gmail account via Mandrill from my RackSpace Cloud server was taking up to 10 minutes to arrive in my Gmail account! 10 minutes may be fine for sending newsletters, but if a customer is in the middle of the checkout process and has to wait 10 minutes for us to respond to his request for help on a forgotten email, we've lost the client.

I started by checking my Mandrill account. I have the free account (up to 12,000 emails a month for free), since I only use it for transactional emails. DKIM and SPF were working, domain was verified, reputation excellent... I saw nothing there that indicated that there was a problem. Their knowledge base had no info on the problem, and since I have a free account, they don't offer support (and I can't blame them ;->).

When reading about the problem, I saw that other Mandrill users were having the same problem. I also saw that Mailgun (owned by RackSpace) offered 50,000 free emails per month for RackSpace cloud users, and thought I would give it a whirl.

After setting up the DNS records and getting the domain verified, I realized that I had PrestaShop configured to send emails via the PHP mail function, and then had Mandrill set up via Postfix. I would assume that is slower than using SMTP directly (which means that my problem may have been a configuration problem), but since I had come this far (and since Mailgun has more free emails per month), I decided to set up Mailgun as my PrestaShop SMTP server.

My tests with Mailgun were mostly arriving in my Gmail account within a couple of seconds, with one taking almost 30 seconds, but it looked acceptable. Gmail's DKIM and SPF authentication tests all passed.

For the moment, I'll stay with Mailgun. I will keep an eye on delivery times, and switch back to Mandrill if I have problems.