Occasionally SMTP mail fails on server for no known reason. To fix it, we send out a mail from an email client, it goes through and then server resumes sending out mail without errors. No settings are ever changed. At one point we thought that a certain character in the email body might be causing an issue but we have never been able to pinpoint what it is or if that is actually what is happening. HELP!!!!

Just to clarify, are you using the Send Mail script step with the "Send via SMTP Server" option?

Yes.

One new piece of information has surfaced, upon opening a mail client (MacMail) there was a pop-up window name "Verify Certificate".

Although this does not usually pop-up on the other workstation, could this cause FileMaker to not send via SMTP? Once the certificate is

verified, and since all requests are generated from the same LAN, all subsequent SMTP requests are granted, however if FileMaker is the

first to attempt to send via SMTP, could this be causing the issue?

Also, since the person who uses the main workstation is usually at work everyday, and is more often than not sending an email before

FileMaker is used to send out mail, it would be safe to assume that somehow they are related, because this person has taken some days off

and the problem has been consistently happening each day.

If this is a 'verify certificate' issue, can FileMaker do that, or are there some settings within the SMTP setup that will verify?

Also, SMTP requests outside of this LAN still work when they do not work onsite.

I'm assuming you are being asked to verify the certificate because it expired. If that is the case, and if the certificate is updated on the SMTP server, this won't be an issue.