Anyhow, the most critical series of error messages is the 5xx one, and especially the ones from 550 to 559.
In particular, you will probably get a lot of 550 SMTP error codes – that is, a problem that concerns the recipient's email address.
You should contact your ISP and ask them to allow you as a certified sender.
Of course, with a professional SMTP provider like turbo SMTP you won't ever deal with this issue.
You should contact the recipient otherwise and get the right address.
It's a (not very clever) strategy to prevent spamming.
Each email application has slightly different steps for setup. This takes you to the main interface screen for Squirrel Mail. Email is not being received when forwarded to free email services such as Gmail, Yahoo, or Hotmail and other ISP's that provide email service such as AOL, Comcast, Cox, etc.
Every time you log into your webmail account, your computer's IP address is recorded.A helpful overview of Horde Groupware If you find some of your emails end up your recipients Spam folder, arrive late, or sometimes don't arrive at all, this article can help you improve the deliverability of the messages you are sending.Why Am I Getting Duplicate Messages in Outlook 2002?And here's a list of the main SMTP error or reply messages, with an explanation and a tip about what to do. It's normally a transient error due to a message overload, but it can refer also to a rejection due to a remote antispam filter.If it keeps repeating, ask your SMTP provider to check the situation.Every mail server is unique, and so are their error responses.It's not always easy to decipher what they're trying to tell you, so we've collected a list of the most common error messages and their variations so you can figure out what to do about it.This usually means the inbox you're sending to or from is full, or your mail routing setting in the zone editor is wrong. On the left are your email folders, by default, Round Cube will always show you POP POP, also known as POP3, is an E-mail protocol that is used when people wish to have a copy of their E-mail messages, along with any attachments, to be downloaded to their computer for viewing.D Occasionally SSL Certificates are reissued and this causes email clients to prompt users to take action after the certificate is changed.The first one defines whether the server has accepted the command, fulfilled an action, run into a temporary issue, encountered an error etc; the second and the third one refine the description further, stating if there's been a syntactic problem, or a connection trouble etc.Unfortunately, different servers sometimes use these codes in a different way, making the whole thing even more complicated...