Title: Could not authenticate.
Last modified: April 4, 2022

---

# Could not authenticate.

 *  [Terence Milbourn](https://wordpress.org/support/users/pubdirltd/)
 * (@pubdirltd)
 * [4 years, 2 months ago](https://wordpress.org/support/topic/could-not-authenticate-6/)
 * Two of the other SMTP plugins in the repository work absolutely fine with the
   same credentials, but all I can get from this plugin is “wp_mail_failed – SMTP
   Error: Could not authenticate.”

Viewing 1 replies (of 1 total)

 *  Plugin Author [MailerSend](https://wordpress.org/support/users/mailersend/)
 * (@mailersend)
 * [4 years ago](https://wordpress.org/support/topic/could-not-authenticate-6/#post-15698194)
 * Hi Terrence,
    I’m Agathe, MailerSend’s project manager.
 * We’re sorry to hear you’ve encountered an error while attempting to send via 
   SMTP. I haven’t been able to find your account, would you mind sending an email
   to [info@mailersend.com](https://wordpress.org/support/topic/could-not-authenticate-6/info@mailersend.com?output_format=md)
   so we can check?
 * We recommend you run through some troubleshooting steps to resolve this as usually
   this type of problem can happen for the following reasons:
 * Wrong username or password: these fields are both case-sensitive, so you need
   to make sure both are exactly as shown in your account and that your provider
   is not changing them to lowercase or uppercase.
 * Sender email address: ensure the ‘from’ address you have opted to use matches
   the domain you’ve verified in your MailerSend account and is entered in lowercase.
 * Security settings: if you are testing MailerSend’s SMTP using a local client,
   you’ll need to make sure you do not have a firewall blocking the connection. 
   You might find you need to set your firewall software to allow SMTP sending using
   port 587.
 * I hope that helps, but please feel free to let us know if you continue to have
   problems.
 * Regards,
    Agathe.

Viewing 1 replies (of 1 total)

The topic ‘Could not authenticate.’ is closed to new replies.

 * ![](https://ps.w.org/mailersend-official-smtp-integration/assets/icon.svg?rev
   =3444657)
 * [MailerSend - Official SMTP Integration](https://wordpress.org/plugins/mailersend-official-smtp-integration/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/mailersend-official-smtp-integration/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/mailersend-official-smtp-integration/)
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 * 1 reply
 * 2 participants
 * Last reply from: [MailerSend](https://wordpress.org/support/users/mailersend/)
 * Last activity: [4 years ago](https://wordpress.org/support/topic/could-not-authenticate-6/#post-15698194)