EXIM retry times are not being observed ? too much time

+secondarymx * F,4h,5m; G,16h,1h,1.5; F,4d,8h * * F,2h,15m; G,16h,1h,1.5; F,4d,8h The blurb in the config file says this will attempt to resend every 15 minutes for 2 hours, then longer intervals for the next 16 hours. It's been happening for some time, that an email will fail and it is next attempted only every hour. 2021-11-11 13:54:24 1mlFD7-0001hT-Uq H=mx.of.some.recip.tld [216.x.x.x]: SMTP error from remote mail server after end of data: 451 4.7.1 Service unavailable - try again later 2021-11-11 13:54:25 1mlFD7-0001hT-Uq == recip@recip.tld R=lookuphost T=remote_smtp defer (-46) H=mx.of.some.recip.tld [216.x.x.x]: SMTP error from remote mail server after end of data : 451 4.7.1 Service unavailable - try again later 2021-11-11 14:52:43 1mlFD7-0001hT-Uq Sender identification U=username D=sender.tld S=sender@sender.tld 2021-11-11 14:52:44 1mlFD7-0001hT-Uq => recip@recip.tld R=lookuphost T=remote_smtp H=mx.of.some.recip.tld [216.x.x.x] X=TLS1.2:ECDHE-RSA-AES128-GCM-SHA256:128 CV=no C="250 2.0.0 Ok: q ueued as 0CEE590000BC" 2021-11-11 14:52:44 1mlFD7-0001hT-Uq Completed
I've got another example of a message that attempted to se sent every 1 hour like clockwork for 5 days traight before finally timing out. FOr that one, the log is full of: T=remote_smtp defer (-53): retry time not reached for any host for <- number is usually 50-something Please explain ?