I manage a web app that issues emails using the users' smtp credentials, and today I encountered a failure which I don't understand.
The smtp credentials in question are trying to make use of smtp-relay.gmail.com. Using a telnet-style approach, I can authenticate with this server and these credentials, but I cannot send mail. (See code block below.) Could it be that the user in question is allowed to connect but just not permitted to send email through this relay? Is this a common characteristic of mail relays? I confess I have little experience with email servers.
openssl s_client -crlf -connect smtp-relay.gmail.com:587 -starttls smtp
# ...
250 SMTPUTF8
EHLO example.com
250-mx.google.com at your service, [207.183.229.82]
250-SIZE 35882577
250-8BITMIME
250-AUTH LOGIN PLAIN XOAUTH2 PLAIN-CLIENTTOKEN XOAUTH
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-CHUNKING
250 SMTPUTF8
AUTH LOGIN
334 VXNlcm5hbWU6
dXNlcm5hbWU=
334 UGFzc3dvcmQ6
cGFzc3dvcmQ=
235 2.7.0 Accepted
MAIL FROM:<[email protected]>
550 5.7.0 Mail relay denied [207.183.229.82]. q16sm4967413pdn.0 - gsmtp
read:errno=0
TMI:
The application is a Ruby on Rails app, and the error which the following raises is an EOFError: end of file reached:
my_message # => #<Mail::SMTP:0x0000000a658da8 @settings={:address=>"smtp-relay.gmail.com", :port=>587, :domain=>"example.com", :user_name=>"[email protected]", :password=>"mypassword", :authentication=>"login", :enable_starttls_auto=>true, :openssl_verify_mode=>"none", :ssl=>nil, :tls=>false, :ca_file=>"/etc/pki/tls/certs/ca-bundle.crt"}>
my_message.deliver # => EOFError