The curious case of auto forwarding emails

Storage in the cloud is considered as a commodity. Cloud based free mailbox providers have been rolling out features and offers like unlimited storage, cloud based drive, large attachment support, etc. to acquire new customers. However, professional or enterprise email has been a little slow in making the shift to the cloud. According to a Gartner report, by the end of 2014 around 10% of enterprise email would have made the shift to cloud email and collaboration services. While this 10% itself is a very healthy number, 90% of enterprises still rely on some variant of locally hosted email solutions. Local installations of any enterprise software are constrained by limited storage along with other resources like computing power and network throughput, while all these resources in the cloud are virtually unlimited.

Enterprise email users are used to getting notifications from their IT administrators warning them about their mailbox quota exceeding the allowed limit. This can be quite annoying, since the expectation is to delete some mails. For a majority of executives anytime access to all their email archives is crucial. Deleting some emails due to quota limitations might not go well with them. Apropos to the quote 'Necessity is the mother of inventions', some ingenious folks have found a work around to make their mailbox virtually unlimited in size. All they need to do is to create an account with a free mailbox provider and forward all mails coming to their office account to the free mailbox account. The free mailbox works like an archive that is always available and also offers a convenient tool to search and locate desired mails when needed. While this arrangement serves the purpose, it might be detrimental for the reputation of the forwarders email system. Let us look at some of the factors responsible for hampering the reputation:

While forwarding emails, Mail Transfer Agents (MTA) of some email systems may replace the original sender's domain with its own domain. When this happens, the email system unknowingly relays spam with its own identity and the free mailbox provider who receives the forward emails feels that the MTA is a source of spam. The situation might aggravate with more such spam getting forwarded and leading the free mailbox provider to cutback the reputation of the sender's MTAs domain as well as IP address.

Some MTAs while forwarding emails may remove or shuffle headers of the original email. This may cause the DKIM signature of the email to fail. When this happens, the forwarded emails might either bounce back or get delivered to the spam folder. Repeated occurrence of DKIM signature failing can lead to the reputation of the MTA to shrink further.

Free mailbox providers usually rely on third party providers of reputation blacklists. There is a high chance that if one mailbox provider identifies and blocks traffic from a particular MTA, then other mailbox providers might follow suit. Imagine a situation where outbound mails of all users of a particular organization being rejected due to the poor reputation of the organizations mail system, and all this because a handful users of the organization chose to forward their incoming mails to a free mailbox provider. I am sure no IT administrator wants to get in such a soup.

One might also argue that forwarding of incoming emails to a third party is breach of the organizations security policy. Hence organizations that are sensitive about their data should not allow forwarding of incoming emails. For organizations who do allow forwarding, they should ensure that they filter out spam, do not modify any headers of the email and also add an extra header indicating that the mail is being forwarded by the MTA.

Related Articles

Auto-forwarded emails could be a huge problem Read more	Why Forwarding your Email is a BAD idea Read more