There have been a number of reports with intermittent problems experienced when using SMTP with gmail posted here to the forum over the last year or so. What's odd is that some people seem to be able to get this to work for them and others have problems like you describe and I haven't seen any definitive post that documented what does and doesn't work with GMail.
Good point and I know the following are definitely the settings for Gmail:
Plain password authentication
I couldn't find definitive answers in this (or any other) forum so felt the need to raise it as a bug even though there appears to be no solution. I simply need to see that officially from FileMaker before deciding on the next step (360Works email?)
Compiling a log of the replies from the SMTP server would be a huge step for us. At least we'd have more information than error 1506............
It's been hard to nail this down as a bug as opposed to issues with gmail. I do have one SMTP bug documented in the system I maintain here in the forum: Email header malformed when using SendMail
This is one of many acknowledged bugs that can be found in the Known Bug List here in the Report an Issue section of the forum.
It can also be downloaded as a database file from: http://www.4shared.com/file/8orL8apk/FMP_Bugs.html
Thank you for your posts.
The error -1506 is a generic error message. PhilModJunk is correct (Thank you) that a lot of users have reported problems sending emails to the gmail server, and some users don't have a problem. A workaround is to use a different mail server than gmail. At this time, we do not know what is causing some users to receive the error.