I used to get green ticks appearing as each copy of a newsletter was sent.

Now I get one green tick and subsequently lots of characters that look like Unicode rendered in a non-unicode setting.

It looks like all the newsletters are being sent, and when I view the newsletters they're fine, and I've not heard back that any are arriving illegibly, so I s'pose it's not really a problem, but...

Zencart 1.3.7, installed on Linux at vowleyfarm.co.uk/VFShop137.
Yes I've searched here but not seen an answer.
It could be due to upgrades at my host, but I didn't notice it near to any changes there, but since I don't often send out newsletters that's not very conclusive.