Because of the host of different email servers and clients out there, it is easy to have a problem with configuring email or an SMTP host at some point; it’s more common than you may think. This guide will explain the top five issues most people have with SMTP configuration at some point.
Incorrect Username or Password
Many problems start by accidentally typing in the wrong username or password. Depending on your client, you might see a pop-up that asks you to enter your password, and entering it incorrectly can cause sending mail to fail.
Depending on your client, you might also need to change the way you enter your username. For instance, you might need to enter the entire email address as a username, which looks like username@exampledomain.tdl. For a Gmail user whose username is Adam123, that means entering it as Adam123@gmail.com. For the same user using hosted email from a website called example.se, this would be Adam123@example.se. If you are using hosted email on an owned website, navigate to your domain and add “/webmail” to see whether your username and password work.
It is also possible you are entering the wrong password altogether, in which case you will need to reset it.
Sometimes, you may need to simply type in your username and password again even if you did it right the first time, especially with Apple Mail. Sometimes, the first instance of sending this information gets corrupted, but typing it all out again should remedy the issue.
Server Not Found
First and foremost, ensure that you are online. Chances are good that you are online if you can read this article, but view a favorite website to verify. If you are trying to send email through a new domain or one that you have recently pointed elsewhere, then your DNS settings have most likely not finished propagating. This can sometimes take a day but can also take two or three days in the worst case.
Make sure that you also use password authentication rather than any other kind.
Verify that your Internet Service Provider has not blocked port 25, which is standard for outgoing. If it is blocked, you may also opt to use port 587 instead to send out emails. This is a simple configuration step.
Mailbox Full / Quota Exceeded
This is often a problem when you are trying to send an email to someone whose inbox is full. You can verify if this is the case by sending an email to that same person with a different email address. If this is the case, then you will just need to tell this person about the issue. If not, the problem is due to the fact that you configured your account to store sent messages on the server where your mailbox is, especially when the mailbox is just about full.
No Such Address
This is an error that another user may have trying to send you emails. This is not a configuration error as it simply is a matter of waiting for your configuration settings to propagate. When you change your DNS settings or mail provider, you may need to wait up to three days before you can receive emails as normal.
Relaying Denied
When this happens, make sure that your client has password authentication enabled for the SMTP server. This is something that is not always set by default. Make sure that your full email address is being used as the username as not all programs accept just the username. Finally, make sure you wait enough time if you have recently changed your DNS settings.
