Many people take advantage of “email forwarding” – the ability to easily forward email from your domain onto for example your hotmail or gmail or ISP home address.
Sounds a perfectly good thing to do, and what harm can it cause? Actually forwarding is a big problem that causes headaches for the sender of the email, the email provider that does the forwarding, the email server that accepts the forward AND the recipient! In short it can cost a LOT of time and money for all involved!
Lets understand why:
Lets say your name is Julie, and you have the domain test.com. You setup an email forwarder for julie@test.com to forward to your julietoo@hotmail.com, and all your email arrives very conveniently for you at Hotmail for you to read, and process in the normal way.
The email service provider that runs test.com for you though has a problem - you probably expect that ANYTHING sent to julie@test.com is forwarded on – including all the spam that you’ve been getting lately. Lets say you get 10 emails a day on average. For most email addresses and/or domains that have been use for more than a year, you may have 10 SPAMs coming in for every legitimate email. This means that the test.com email server is going to actually have to forward 100 additional SPAMs a day to hotmail.
Of course the hotmail Mail Firewall sees this behavior (100 SPAMs a day from the same sending machine) and quickly blacklists (refuses ALL messages from) the test.com email server. Not only is the email server that runs test.com seen as a SPAMMER, test.com is now seen as a SPAM SOURCE. This means that the reputation of both your domain and your service provider is damaged.
Additionally, if you have setup a catch-all email address - i.e. @test.com so that sales@, info@, jules@, etc all work and go to your hotmail account via a forward you have an even bigger problem. If a SPAMMER tries a dictionary attack against test.com - sending hundreds or thousands of emails to made up addresses @test.com then the test.com email service provider will be forwarding ALL of those messages on to hotmail, which will have the server blacklisted within minutes.
Suddenly you stop getting ANY email into your Hotmail account that you expect from your forwarded account. Who do you call ? Well, you will be lucky if you can actually get anyone from a large ISP (Verizon/Comcast/Embarq, etc) or large mail provider (hotmail, gmail, yahoo) to talk to. And even if you could you would get the no problem here, must be on the other end response, because as far as that provider is concerned, all they are doing is saving you the headache of getting an additonal 110 SPAMs a day (your 100 SPAMs plus the 10 legit emails). Remember, when you deal with large companies that process millions of emails an hour, its impossible for them to really care or worry much about a few legit emails that get blocked. Blocking the massive SPAM inflow is much more important, because if their customers get thousands of SPAMs each day, they would simply not use and/or pay for their service.
So, next you call the provider of test.com to investigate the problem on their side. The answer you will get is: "no problem here, we see that hotmail.com is blocking our attempts to send email". The provider may or may not be able to get hotmail.com to take action and fix this. More often than not, this is very time consuming for the providers to track down a human on the opposite side that is able to fix the problem. So email remains broken, or in a state of flux (sometimes works, sometimes does not, depending on whether hotmail removes the blacklist after a period or not, and depending on how much SPAM comes through the auto forward).
This is clearly not an ideal situation, and it gets worse. Some domains create SPF (Sender Permitted From) records to deal with forged emails. If the SENDER of an email has an SPF record, and the RECIPIENT of and email uses a forwarding account, things go haywire so to speak. More often than not the RECIPIENT side email firewalls will block the message unless the FORWARDING service provider has all of its mail servers added to the SPF record. This is difficult to do, and if this information changes, email breaks.
Finally, to avoid the forwarding of SPAM mess discussed above. most providers (if they have any clue at all) will fully SPAM filter all email BEFORE its forwarded, so they avoid getting blacklisted for forwarding SPAM. This means that an email will take the following path:
SENDER :: FORWARDER_FIREWALL :: FORWARDER :: RECIP_FIREWALL :: RECIPIENT
Either of the 2 firewalls - FORWARDER or RECIPIENT can possibly reject a message due to it matching:
1. SPAM or SPAM-like content (often the case if you forward off color jokes, or other chain letter type email)
2. VIRUS or SPYWARE
3. DANGEROUS file names or file contents (like a "cool" screensaver you found)
4. LARGE FILE ATTACHMENTS (multiple photos for example)
Each of the firewalls will have different policies (support FORWARDING firewall allows 20 MB attachments, but RECIPIENT firewall only allows 5 MB attachments because its a FREE ACCOUNT!)
Troubleshooting where the email was blocked wastes the time and resources of each provider (FORWARDING and RECIPIENT) neither of which will be sure where the problem really is unless they investigate manually, which generates zero profits, only costs for the providers.
Many web hosts are now banning email forwarding to third party email accounts, removing the capability all together. And the result for these hosts is a serious decrease in spam complaints against their servers. Richweb does not ban email forwarding just yet, but it is inevitable that for most providers that forwarding email externally is just too much trouble, and the benefits to everyone by turning it off, far outweigh any benefits of having this so called “feature”.