Email Deliverability Affected by Other Companies?

[Jeff_Smith3]

I had a situation where a webinar invite email went to a prospect. She clicked to register, filled out the form, but did not receive the confirmation email. I checked her history and discovered that the email bounced, with a bounce code of 550 ("User’s mailbox was unavailable (such as not found)". The activity details read, "550 rejected [IP address] is temporarily blocked. Contact support". I thought this was odd, since she had received the invite email only moments before being blocked from the confirmation.

After checking with support, I was told, "It looks like the spam bounce was caused by the shared IP being temporarily blacklisted by Spamcop due to another Marketo account hitting a spam trap. We have addressed the issue with the responsible party and have requested delisting with Spamcop. We realize it is frustrating to have your email deliverability affected by someone else's mistake." I was also offered some solutions by support, which was very helpful, but I'm wondering if anyone else has ever encountered this? This isn't an area that I know a ton about, but I was surprised to learn that a different company's email practices could adversely affect my email deliverability, uncommon though it may be. Does anyone have any documentation on this?

[Anonymous · Accepted solution]

I had similar issue a couple of times before for a couple of customers.

SpamCop lists IPs for one of two reasons. Either the email hit SpamCop spam trap addresses, or a SpamCop user has reported the email originating from the IP as unwanted. Most of SpamCop’s spam traps are previously valid addresses that have not been used for 12 months or longer.

SpamCop is a dynamic blacklist, which means that listings typically resolve themselves within one business day. You can request delisting by filling out an online form. If you triggered a SpamCop listing, it likely means that you have stale year old email addresses or the email list acquired contains spamtraps, issues that should be addressed strategically.

Typically IP addresses are shared among Marketo customers. Marketo team continuously monitor and works to de-list these IP addresses from blacklists. They also inform the customer who might have sent emails that might have caused this.

There are a couple of options if you want to better control your deliverability and not get affected by other companies who share your email sending IP address. You can upgrade to premium IP addresses reserved for customers who hav demonstrated better email practices and have no spam complaints and meet strict thresholds for email deliverability.

Or you can move to a dedicated IP address all together where you do not get affected from any other company's activities. We ended up going this route.

Hope this helps

Rajesh

[Jeff_Smith3]

Great explanation. Thanks Rajesh! It makes sense that with all of our databases, there will be some overlap of IP addresses. I'll look into those possible solutions.

[Anonymous]

I've had the exact same issue. So if this bounce errors happened, Marketo killed the IP that caused my bounces. Does this mean I have to try re-sending emails that bounced?

Does anyone know what bounce error indicate that the email is 100% not valid anymore? I've been talking to support about some bounce reasons and read some articles here, but I am still not able to identify what bounces are caused by shared IP, invalid email, etc..