I need to switch lots of clients from Mandrill and decided to test Mailgun first. I moved one small customer over as a trial but I’m already seeing delivery failures to legitimate email addresses.
It seems like the recipient’s email provider is blocking emails coming from Mailgun’s servers. This is really concerning because I’ve heard from other sources that Mailgun might have delivery rate issues compared to other major email services.
Has anyone here used Mailgun before and run into similar problems? With Mandrill these kind of blocks almost never happened. I’m worried about moving 20+ business accounts to a service that might have poor inbox delivery rates. These are transactional emails for online stores so getting them delivered is critical for my clients.
yeah, bigpond is tough with third-party services. definitely reach out to mailgun support for whitelisting help - they can guide you. also, make sure your SPF and DKIM settings are correct; they often cause delivery probs, not the service itself.
I’ve used Mailgun for two years across multiple client accounts. Delivery rates are solid once you get through the initial setup pain. That BigPond error happens all the time with new Mailgun accounts - their IPs need time to build reputation. If you’re moving high-volume clients, get a dedicated IP. The delivery difference between Mailgun and Mandrill isn’t huge, but Mandrill had better sender reputation out of the box. Run more test campaigns first, especially to Gmail and Outlook, before switching everything over.
BigPond blocks are super common when switching providers, but here’s what most people don’t get - your domain’s sending history matters way more than the ESP’s IP reputation. I moved 15 clients from Mandrill to Mailgun last year and hit the same blocks at first. IP warmup wasn’t the fix - proper feedback loops and complaint handling were. BigPond cares about bounce rates and complaint ratios from your domain, not the sending server. Clean your lists before you migrate and watch Mailgun’s analytics like a hawk. Mandrill handled reputation stuff more transparently, but Mailgun makes you do the heavy lifting on monitoring. You’ll get back to Mandrill’s delivery rates, just expect 2-4 weeks of babysitting the setup.
Went through the same thing last year switching from Mandrill - Australian ISPs definitely give Mailgun grief at first. That BigPond IB112 error usually clears up after 2-3 weeks of consistent sending, but who’s got time to wait when you need transactional emails working now? Here’s what actually worked: Contact Mailgun support for a subdomain reputation reset and get your authentication records set up right away. Mandrill already had relationships with the big ISPs, but with Mailgun you’re building reputation from scratch. One thing that helped - start with your highest-volume client, not your smallest. Sounds backwards but it builds sender patterns way faster. And make sure your clients have proper unsubscribe handling because complaints will torpedo your reputation on any new platform.
BigPond blocks suck. I dealt with the same nightmare at my company.
Skip fighting email providers and their reputation games. I built a fallback system with Latenode that monitors delivery failures and auto-switches between email services when one gets blocked.
My setup catches those 554 errors instantly and routes through backup services like SendGrid or Amazon SES. Takes 30 seconds to failover vs losing emails completely.
With 20+ business accounts, this beats waiting for Mailgun’s reputation to improve. Keep Mailgun as primary but get instant backup when ISPs block you.
I added monitoring that tracks delivery rates per domain and adjusts routing automatically. BigPond keeps blocking Mailgun? Those emails permanently route through backup.
Saved us thousands in lost sales from dropped transactional emails. Way better than juggling multiple SMTP configs or waiting weeks for reputation recovery.
mailgun’s deliverability is decent, but mandrill was way more reliable from day one. that bigpond error’s annoying but happens all the time - warm up your sending domain gradually instead of going full volume right away. test with a couple smaller clients before moving all 20+ accounts over.
BigPond’s been really aggressive with their filtering lately - not just Mailgun, but pretty much all transactional email providers. That IB112 error means their system thinks your sender reputation is sketchy. Usually fixes itself in a few weeks once you’ve established trust, but you can’t wait that long for business-critical emails. Set up a backup SMTP service for the first month while your main Mailgun reputation builds. I’d also start with lower volume and ramp up gradually instead of switching all 20+ accounts at once. This isn’t really a Mailgun issue - it’s just how receiving servers treat any new sender.