This could be a variety of things:

Spam trigger words.
Sending domain or reputation is going down.
Complaint ratio too high.
Too many hard bounces
Engagement is low
If your emails have a marketing nature, MailChimp is definately not going to be your best solution
Do you have a dedicated IP? If not, the range you are on might be suffering from other users abusing it.

If your mail is going to the spam folders, you need to look at the following...

Back-end setup: spf, dkim, rdns, etc...
IP / domain reputation: any domain / IP that is associated with the mailing. Also test username.
Content: everything in the message body / mailing address, subject line, plus your template.

You need to test everything step-by-step and isolate the problem and fix it.

You ideally want to know the domain makeup of your list(s) and create seed accounts for the domains with the highest percentage of users. Then use the seeds to test your inbox placement before sending your message.

For many, AOL, Hotmail/Outlook, Gmail, Yahoo and parent domains using the same mx, can makeup as much as 85-90% of their list. So at the very least, you should start with them and any other seed accounts you can set up or acquire.

For small domains / GI, which it's just not possible to get accounts for, you could set up spamassassin with razor and pyzor add-ons and use it to test with. These domains combined will typically makeup 10% or less of your list.

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Send yourself a test email and then look for the sending IP address. Run that IP address through MXToolbox's blacklist checker as well as SenderBase and SenderScore. If it's on a blacklist or has a low SenderScore, contact MailChimp's support and ask them to move you to another IP.

However, there is a chance that you might have gotten your domain on some internal blacklists.

Which TLDs are you hitting the spam folder with?

Hey All,

Ran some tests and it appears the alt tags were missing. Added those in and the problem seems to be solved. Thanks for all of your help!

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