Pretty much all internet mail servers use some sort of spam filtering. The most common reason for receiving bounced back emails is because the incoming mail server thinks your email may be spam. When this happens, you will usually receive a message similar to the following:
SMTP error from remote mail server after MAIL FROM:<(Your email address)>:
553 5.3.0 alph132 DNSBL:RBL 521< (The IP Address your sending from) >_is_blocked.__For_information_see_(Information about removing the block)
If you receive a message like the following, you should first follow the link they provide you with, or follow any other included instructions. IP address, email accounts, and domains can only be un-blocked, by the organization that placed the block. RDO Servers has no way of manually removing a block on another hosts server. We constantly monitor the status of our IP address on all major public blacklists. However some organizations (such as AOL, Microsoft, & SBCGlobal) do not provide a way to check the blacklist status of a IP address. In these cases, we do not know they are blacklisted until we are notified by them.
There are many reasons your email messages could be flagged as spam
The most common reason is because you or your account is in fact sending out spam. This could be going on without you even knowing it. Someone could have gained access to your email account. Someone could have hacked your website and inserted malicious code for sending out spam, or someone could be “spoofing” your email account. (Sending email from their own server, but making it look like you are the one sending it). If we see spam messages from your account, in our outgoing mail logs we will notify you immediately.
Shared hosting customers that use a shared IP address may be affected by another user on the same IP address. If someone else causes our IP address to be blacklisted, it will affect everyone on the same IP address. This is something we take very seriously and will take appropriate action to maintain our IP reputation on all blacklists.
Some blacklist organizations will add an entire IP range, instead of only the offending IP address. This is not common practice, but it does happen at some of the smaller blacklist organizations. This can cause your IP address to be blacklisted due to someone else’s spam, even if they are not on the same server.
Incorrect MX, rDNS, PTR, spf, or DKIM records. Some mail servers will check other values associated with your domain name, in an attempt to make sure your IP address is authorized to send email for your domain. (to prevent spoofing). Sometimes having your DNS setting incorrect can cause your emails to be blocked. If you receive bounced-back emails that site a problem with your DNS settings, contact our support team if you need assistance.