(I've starred out the address & password for privacy reasons. When this happens, I can go to http://www.gmail.com and login, and I will be presented with a captcha to solve before I can do so. Once I have solved the captcha and login the Swift email will work as expected.Fatal error: Uncaught exception 'Swift_ConnectionException' with message 'Authentication failed using username '********'' and password '********'' in /home/foxcraft/public_html/includes/Swift/lib/Swift/Connection/SMTP.php:414 Stack trace: #0 /home/foxcraft/public_html/includes/Swift/lib/Swift/Connection/SMTP.php(331): Swift_Connection_SMTP->runAuthenticators(''********''', ''********''', Object(Swift)) #1 /home/foxcraft/public_html/includes/Swift/lib/Swift.php(264): Swift_Connection_SMTP->postConnect(Object(Swift)) #2 /home/foxcraft/public_html/includes/Swift/lib/Swift.php(220): Swift->handshake(Object(Swift_Events_ResponseEvent)) #3 /home/foxcraft/public_html/includes/Swift/lib/Swift.php(101): Swift->connect() #4 /home/foxcraft/public_html/includes/classes/TmiGmailer.php(19): Swift->__construct(Object(Swift_Connection_SMTP)) #5 /home/foxcraft/public_html/pages/public/contact.php(100): TmiGmailer->TmiGmailer(''********''', ''********''') #6 /home/foxcraft/public_html/includes/classes/PageDisplayer.php(200): requi in /home/foxcraft/public_html/includes/Swift/lib/Swift/Connection/SMTP.php on line 414
I found another thread about someone who had a similar sounding issue: viewtopic.php?f=52&t=77887&start=0&st=0&sk=t&sd=a
This thread suggests that the user's problem may be volume: apparently Gmail will temporarily kick you out after sending too many emails in a short time. However, I use gmail accounts for a number of different Swift / online contact forms and this problem seems altogether uncorrelated with volume, or with anything else that I can think of. The most recent time that this happened to me was with an account that had work successfully sending out low volumes of emails (10 - 20 total) for over a month. I've also had accounts that have been active longer with no problems.
It sounds like I am tripping some sort of "spam" setting on gmail, but since this issue is so random, I can't diagnose it. Is there anything I can do / setting that I can change to make Gmail a more reliable email host for me?