Ask HN: How can I get a company to stop using invalid email addresses?

I've been using Blur from Abine.com for a while. One of their services, migrated from a previous product called MaskMe, generates masked emails that look like this: "c1f9e2c0@opayq.com", and any email sent to that address gets forwarded to your address. Recently (around a month or so), they started using very long email addresses to forward (e.g. 737rfylmhfbayacam6aatijgei5fcahya5qddjaf2ac6achaamqemicmemmtacxaawuaaiaaea======@opayq.com). This has caused problems with gmail, which will sometimes display certain prompts (e.g. "display images") that cover buttons, forcing me to reload the page to click them.

Now, https://tools.ietf.org/html/rfc5321#section-4.5.3.1.1 states that

The maximum total length of a user name or other local-part is 64 octets.

which the addresses violate. I wouldn't really care, except that it's causing me issues.

Anyway, I don't pay for the service, so I understand I can't demand anything of them as complex as actually complying with RFCs. But I reached out to their support, letting them know the problem I had with screenshots, and also linking to the RFC. I went back and forth a few times, but got nothing more than

"... there are restrictions that keep us from shortening the forwarding address, and reducing the length would take away some of the core functions of masked emails."

Is there anything else I can do to convince them? Or should I drop the issue?