Greylisting is used to prevent bulk e-mailers and SPAM bots from getting their email delivered. Greylisting is a temporary rejection of a message that forces the sending agent to resend it at a later time. Legitimate senders will attempt to retry the message later, while bots and spammers normally will not.
From Wikipedia: "Greylisting (or graylisting) is a method of defending email users against spam. A mail transfer agent (MTA) using greylisting will 'temporarily reject' any email from a sender it does not recognize. If the mail is legitimate, the originating server will, after a delay, try again and, if sufficient time has elapsed, the email will be accepted."
Greylisting is enabled by default on shared mail servers as part of our ongoing battle against spam. Bypassing the greylisting feature can be done at two levels: the Domain level and the Individual level. To disable it, follow the instructions below.
Bypass Greylisting
You will need to contact support; one of our client support representatives will make this modification to your domain settings so that all mailboxes under that domain are automatically bypassed.
Benefits of Greylisting:
- Spam Filter
- The default setting requires no configuration
Negatives of Greylisting:
- The first email between two contacts may be delayed; once the addresses are verified, this process should be instantaneous.