SMTP Error: Could not authenticate.

[eluser]Unknown[/eluser]
Hello everyone,

I got my site built a couple of years ago by contractors and I am now looking after it, although I am not very good at php (so treat me like a beginner pls!) I am ok managing every other aspect of it.

My users have recently started getting this error when submitting a contact us form "SMTP Error: Could not authenticate" even though I haven't touched the code on my site ever since it was built 2 years ago neither have I changed any passwords. I no longer receive contact us forms!

This is the full error

============================================
SMTP Error: Could not authenticate.
A PHP Error was encountered

Severity: Warning

Message: Cannot modify header information - headers already sent by (output started at C:\php\includes\class.phpmailer.php:586)

Filename: libraries/Session.php

Line Number: 671

A PHP Error was encountered

Severity: Warning

Message: Cannot modify header information - headers already sent by (output started at C:\php\includes\class.phpmailer.php:586)

Filename: helpers/url_helper.php

Line Number: 541
====================================================

Any help will be appreciated!!

[eluser]bientek[/eluser]
PHPmailer suddenly stopped working for me too. My CI app also relies on PHPmailer, and suddenly cannot authenticate either (after a year of it successfully working with smtp.google.com, TLS port 587). I suspect that it may be due to a change on the server that my hosting company had just made. (I suspect this because I had just asked several hours earlier for them to check the spam logs for any indication of spam being sent from my server, and since their reply that they had "sent a test email", it now consistently produces this error.)

[eluser]NotDior[/eluser]
Sounds like the sending account was using some kind of authentication for sending e-mail. I know you said that you hadn't changed the passwords or e-mails, but be sure of what account it's using to send the e-mail.

Also check ports to make sure they haven't changed on you.

[eluser]bientek[/eluser]
The settings haven't changed (they are stored in a DB, and I logged in manually using the credentials). The ports settings from the DB have stayed the same. I don't think Google has suddenly changed their ports.