Mailgun: Messages "Accepted" but taking long time to be delivered (or not being delivered)

Question

I'm using Mailgun for a site I maintain, usually Mailgun works great, but I am encountering a strange problem. My script calls the HTTP API to send messages using Mailgun, these then show up in my log as being "accepted", but then take a very long time to be "delivered", often failing to be delivered at all and simply remaining as "accepted". Has anyone experienced a similar error or could anyone suggest a way to fix it? I'm guessing it's in the arguments supplied to the API but I can't for the life of me figure out the problem.

The problem exists for different recipient domains and different times of day.

The JSON log of a problematic message is below. I have, of course, changed addresses and domains.

{
    "tags": [], 
    "timestamp": 1411498829.247304, 
    "envelope": {
        "targets": "my-own-email@address.com", 
        "transport": "", 
        "sender": "noreply@the-site-in-question.com"
    }, 
    "recipient-domain": "address.com", 
    "event": "accepted", 
    "campaigns": [], 
    "user-variables": {}, 
    "flags": {
        "is-authenticated": true, 
        "is-system-test": false, 
        "is-test-mode": false
    }, 
    "message": {
        "headers": {
            "to": "my-own-email@address.com", 
            "message-id": "20140923190027.112157.29352@the-site-in-question.com", 
            "from": "\"the-site-in-question.com\" <noreply@the-site-in-question.com>", 
            "subject": "Dom, your password was reset."
        }, 
        "attachments": [], 
        "recipients": [
            "my-own-email@address.com"
        ], 
        "size": 556
    }, 
    "recipient": "my-own-email@address.com", 
    "method": "http"
}

Greg Kaleka · Answer 1 · 2015-08-14T16:47:13.067

61

If this is happening regularly, it is very likely Mailgun has you on one of their low-tier IP addresses. I imagine this is the default for free accounts, since they don't want to "pollute" their good addresses with new users who may not be serious / legit.

You can check the "quality" of the IP address at a site like Sender Score. Find this line in the Mailgun log of a delivered message:

"sending-ip": "XXX.XX.XXX.XXX"

If Sender Score shows a score in the 70s, that's your problem. Send Mailgun a support ticket, as Chris suggested, and see if they can get you onto a higher quality IP address. I did so and my emails are now being sent from an IP address with a score in the 90s. Haven't had a single delay since.

edited Aug 14 '15 at 16:47

answered Aug 14 '15 at 16:21

Greg Kaleka

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Sender Score is for companies; anything for individual users? – Šime Vidas Dec 01 '16 at 20:02
use https://talosintelligence.com/ for checking IP or domain reputation... – Pablo Martinez Oct 05 '17 at 11:05

score 52 · Accepted Answer · answered Sep 24 '14 at 09:25

52

Whenever a message shows as "Accepted" in the Mailgun logs this indicates that Mailgun has accepted the message and queued it for delivery. The message should be delivered fairly quickly, however it can be queued for a bit of time if you submitted a large amount of messages at once or if the recipient ESP is throttling messages from the IP/domain on your account.

I'd recommend opening a support ticket via your Mailgun account and provide some of the message-ID's so the support team can investigate the exact cause of these delays once the message is submitted to Mailgun.

answered Sep 24 '14 at 09:25

Chris Hammer

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4

This happens pretty regularly with Mailgun unfortunately. Having to open a support ticket every time an IP gets throttled isn't that helpful. – Doug Jan 19 '15 at 04:25
13

It's now May 2016 and this is still an issue. It's not a reputation issue because my app sent out emails after the delayed one and those email were delivered instantly. But once in a while a random message takes 2-3 hours to be delivered. – Costa May 19 '16 at 00:31
1

In my case one-liner mails sent from command line get delivered immediately, but full HTML emails submitted via API are taking forever. – ankush981 Mar 11 '17 at 07:54

score 0 · Answer 3 · answered Jul 05 '20 at 08:15

0

The reason why emails are not delivering when sending to the domain name is due to no Routes being on the account. As a note, Flex plans cannot create routes; only Foundation and higher plans may use this feature.

answered Jul 05 '20 at 08:15

nourza

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score -1 · Answer 4 · answered May 11 '18 at 20:58

For guys using the default Mailgun domain who will end up here like I did:

Mailgun did log my email as 'accepted' and 'delivered', however there was no email received in my inbox.

To fix this, you need to authorize the recipient email address: Read More Here

Mailgun: Messages "Accepted" but taking long time to be delivered (or not being delivered)

4 Answers4

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