HI there on my newsletter pre-check I get this for the Mailgun server IP:

Your IP 143.55.232.11 is blocked on 4 lists:

s5h.net: See http://s5h.net/rbl
dnsbl-1.uceprotect.net: IP 143.55.232.11 is UCEPROTECT-Level 1 listed. See http://www.uceprotect.net/rblcheck.php?ipr=143.55.232.11
dnsbl-2.uceprotect.net: Net 143.55.232.0/24 is UCEPROTECT-Level2 listed because 33 impacts are seen from MAILGUN-, US/AS396479 there. See: http://www.uceprotect.net/rblcheck.php?ipr=143.55.232.11
Sorbs.net: Spam Received See: http://www.sorbs.net/lookup.shtml?143.55.232.11

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Consider cloudflare detection, and check directly with their servers instead of waiting for global propagation

I would like to talk with any of your executive, who can help me to setup the STMP service with Gmass.

Mautic plugin integration
https://www.mautic.org/
Will be really helpfull.
I am thinking to switch to sendgrid because.
Mautic go on spam folder with your SMTP credential

Implement U2F/Yubikey support for 2 factor auth.

This will enable people who can't use their phones in the office, but can use hardware tokens, to take advantage of the 2 factor auth you just implemented.

Allowing a "Reply to" address that is different from the "From" would GREATLY expand the power of the Zapier integration by allowing users of an application to follow the Truthful Routing clause of the CAN-SPAM while being able to receive replies.

Allow Mailgun account email to send emails to mailing lists from Outlook without having to change the outgoing servers. This would be a step between needing to be authenticated (Read Only) and Allowing people in the mailing lists to post things.

This way the owner of the mailgun account can send emails from Outlook to their mailing lists, but no one else would be able to do this.

Please add the possibility to forward feedback loop emails so that we can use other tools to analyse them in more detail then Mailgun provides...

Universal links in iOS 9 make it possible for our links to open directly in our app. Unfortunately redirects break this behavior, so Mailgun's click tracking breaks our universal links.

A simple workaround would be to allow us to set an arbitrary CNAME. I could then point that CNAME at a CloudFront distribution. That way we could serve an apple-app-site-association file and redirect all other requests to mailgun.

We could then intercept the click tracking links in the app, and fetch the click tracking link to record the click and get the redirect target.

The current URLs used for tracking link clicks are quite long. Offering a way to shorten them via Bit.ly or perhaps an custom shortened URL would be helpful.