SMTP Waiting

Hello - 24 hours ago we started having a few weird issues.

Client can't get to any Financial sites and login. The login will time out. If I disable Web filtering or bypass the source IP, it's fine. I only mention this issue here as they started at the same time.

Also, we have about 50% of e-mails getting stuck in SMTP spool in 'waiting'. We haven't made any big changes but rolled back to a month ago to be sure and still stuck in waiting. Error messages vary but are along the lines of the logs below. There's multiple different dest domains, but again, most have a similar messages. This only occurs on outbound mail. We have a valid license and after 3 hours with support they said they were unsure and had to let me go as their shift was over . . . . . .

Verified client domain is not on any blacklists. 


2018-11-06 13:13:00 Remote host [67.219.X.X] closed connection in response to sending data block.
2018-11-06 13:18:59 SMTP error from remote mail server after RCPT TO:<REDACTED>: host [52.21.X.X]: 421 Service Temporarily Unavailable

  • In Web Filtering, add an Exception for 'SSL scanning' and 'Certificate trust check' for 'Finance/banking'.

    What do you see in the logs when the first attempt was made to deliver one of the emails?

    Cheers - Bob