Title: Error: Could not authenticate.
Last modified: June 18, 2023

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# Error: Could not authenticate.

 *  Resolved [lordsnake](https://wordpress.org/support/users/lordsnake/)
 * (@lordsnake)
 * [2 years, 11 months ago](https://wordpress.org/support/topic/error-could-not-authenticate/)
 * > > I am suddenly not able to send emails for some reason from one of my sites.
   > > 
   > > I have even reset the smtp credentials as well, but still no joy.mailersend
   > > have confirmed there is no issue at their end and the credentials work fine.
   > > any idea what is wrong?
   > > Versions:
   > > WordPress: 6.2.2WordPress MS: NoPHP: 7.4.33WP Mail SMTP: 3.7.0
   > > Params:
   > > Mailer: smtpConstants: NoErrorInfo: SMTP Error: Could not authenticate.
   > > Host: [smtp.mailersend.net](http://smtp.mailersend.net/)Port: 587SMTPSecure:
   > > tlsSMTPAutoTLS: bool(true)SMTPAuth: bool(true)
   > > Server:
   > > OpenSSL: OpenSSL 1.1.1p 21 Jun 2022Apache.mod_security: No
   > > Debug:
   > > Email Source: WP Mail SMTPMailer: Other SMTPSMTP Error: Could not 
   > > authenticate.
   > > SMTP Debug:
   > > 2023-06-14 18:32:38 Connection: opening to [smtp.mailersend.net:587](http://smtp.mailersend.net:587/),
   > > timeout=300, options=array()
   > > 2023-06-14 18:32:38 Connection: opened
   > > 2023-06-14 18:32:39 SERVER -> CLIENT: 220 [smtp.mailersend.net](http://smtp.mailersend.net/)
   > > ESMTP
   > > 2023-06-14 18:32:39 CLIENT -> SERVER: EHLO [managedwp.uk](http://managedwp.uk/)
   > > 2023-06-14 18:32:39 SERVER -> CLIENT: [250-smtp.mailersend.net](http://250-smtp.mailersend.net/)
   > > Nice to meet you, grh34.myukcloud.com250-PIPELINING250-8BITMIME250-SMTPUTF8250-
   > > AUTH LOGIN PLAIN250 STARTTLS
   > > 2023-06-14 18:32:39 CLIENT -> SERVER: STARTTLS
   > > 2023-06-14 18:32:39 SERVER -> CLIENT: 220 Ready to start TLS
   > > 2023-06-14 18:32:39 CLIENT -> SERVER: EHLO [managedwp.uk](http://managedwp.uk/)
   > > 2023-06-14 18:32:39 SERVER -> CLIENT: [250-smtp.mailersend.net](http://250-smtp.mailersend.net/)
   > > Nice to meet you, grh34.myukcloud.com250-PIPELINING250-8BITMIME250-SMTPUTF8250
   > > AUTH LOGIN PLAIN
   > > 2023-06-14 18:32:39 CLIENT -> SERVER: AUTH LOGIN
   > > 2023-06-14 18:32:39 SERVER -> CLIENT: 334 VXNlcm5hbWU6
   > > 2023-06-14 18:32:39 CLIENT -> SERVER: [credentials hidden]
   > > 2023-06-14 18:32:39 SERVER -> CLIENT: 334 UGFzc3dvcmQ6
   > > 2023-06-14 18:32:39 CLIENT -> SERVER: [credentials hidden]
   > > 2023-06-14 18:32:39 SERVER -> CLIENT: 535 Authentication failed.
   > > 2023-06-14 18:32:39 SMTP ERROR: Password command failed: 535 Authentication
   > > failed.
   > > SMTP Error: Could not authenticate.
   > > 2023-06-14 18:32:39 CLIENT -> SERVER: QUIT
   > > 2023-06-14 18:32:39 SERVER -> CLIENT: 221 Bye
   > > 2023-06-14 18:32:39 Connection: closed
   > > SMTP Error: Could not authenticate.

Viewing 1 replies (of 1 total)

 *  Plugin Support [Victoria Sakal](https://wordpress.org/support/users/sakalvictoria/)
 * (@sakalvictoria)
 * [2 years, 11 months ago](https://wordpress.org/support/topic/error-could-not-authenticate/#post-16831311)
 * Hi, [@lordsnake](https://wordpress.org/support/users/lordsnake/)!
 * Thanks for reaching out!
 * This error (“_SMTP ERROR: Password command failed: 535 Authentication failed._“)
   typically means that the SMTP password is incorrect. And because of this, the
   SMTP server you’re trying to connect to is rejecting it.
 * Please, double-check once more the password you’re using with the SMTP connection
   to be sure it’s correct.
 * Also please know, that the _Other SMTP_ mailer option does not use a dedicated
   API, which can lead to potential errors based on your website hosting/SMTP settings.
   In cases where ongoing issues arise while using the _Other SMTP_ mailer, we generally
   recommend switching to a transactional mailer option (it’s all mailers except
   the _Other SMTP_ and _Default (none)_ option).
 * WP Mail SMTP has documentation on setting up each of the available mailers [here](https://wpmailsmtp.com/categories/docs/mailers/).
 * Kind regards

Viewing 1 replies (of 1 total)

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 * 1 reply
 * 2 participants
 * Last reply from: [Victoria Sakal](https://wordpress.org/support/users/sakalvictoria/)
 * Last activity: [2 years, 11 months ago](https://wordpress.org/support/topic/error-could-not-authenticate/#post-16831311)
 * Status: resolved