@danielpunkass yep - and it was accepted by mailroute both times (after being greylisted on the 10th):

May 10 15:46:56 chumdrop postfix/smtp[99381]: 84D7514C98B: host mail.mailroute.net[199.89.1.120] said: 450 4.7.1 <support@redsweater.com>: Recipient address rejected: Policy Rejection- Greylisting challenge offered. Legitimate and well-configured mailservers will automatically retry shortly, and mail will go through. (in reply to RCPT TO command) May 10 15:46:59 chumdrop postfix/smtp[99381]: 84D7514C98B: to=<support@redsweater.com>, relay=mail.mailroute.net[199.89.3.120]:25, delay=13, delays=0.04/0/11/1.3, dsn=4.7.1, status=deferred (host mail.mailroute.net[199.89.3.120] said: 450 4.7.1 <support@redsweater.com>: Recipient address rejected: Policy Rejection- Greylisting challenge offered. Legitimate and well-configured mailservers will automatically retry shortly, and mail will go through. (in reply to RCPT TO command)) May 10 15:52:16 chumdrop postfix/smtp[99884]: 84D7514C98B: to=<support@redsweater.com>, relay=mail.mailroute.net[199.89.1.120]:25, delay=330, delays=328/0.02/0.8/1.5, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 4FfBXb3L5xz1BFXt) May 14 06:46:43 chumdrop postfix/smtp[646551]: C834A1461D5: to=<support@redsweater.com>, relay=mail.mailroute.net[199.89.1.120]:25, delay=14, delays=0.08/0/11/2.9, dsn=2.0.0, status=sent (250 2.0.0 Ok: queued as 4FhQFG3kdJzHpGM)