All other mails I have tried get delivered fine.
Just this one, which is a bit spammy looking, will not get delivered. No error message about non-delivery is returned to me.
I have tried sending to myself directly. Originally the mail had a long text, and by sending about 30 emails, cutting away lines, I narrowed it down to exactly those few words which made the mail undesired.
I tried making a screen shot of the offending text. That made it arrive as expected, so I don't think iCloud OCR the text.
Below is the full text of the offending mail, which I believe is many years old, but still in circulation. Perhaps Apple decided it is about time to end the life of this one :-)
'Doctor Dementia' Tests Your Skills .......
Can you meet these 2, challenges? We've seen this with the letters out of order, but this is the first time we've seen it with numbers.
Good example of a Brain Study:
If you can read this OUT LOUD you have a strong mind.
And better than that: Alzheimer's is a long, long way down the road before it ever gets anywhere near you.7H15 M3554G3
53RV35 7O PR0V3
H0W 0UR M1ND5 C4N
D0 4M4Z1NG 7H1NG5!
1N 7H3 B3G1NN1NG
17 WA5 H4RD BU7
N0W, 0N 7H15 LIN3
Y0UR M1ND 1S
R34D1NG 17 4U70M471C4LLY
7H1NK1NG 4B0U7 17,
B3 PROUD! 0NLY
C3R741N P30PL3 C4N
PL3453 F0RW4RD 1F
U C4N R34D 7H15.
To my 'selected' strange-minded friends: If you can read the following paragraph, forward it on to your friends with 'yes' in the subject line. Only great minds can read this. This is weird, but interesting!
If you can raed this, you have a sgtrane mnid, too
Can you raed this? Olny 55 people out of 100 can.
I cdnuolt blveiee that I cluod aulaclty uesdnatnrd what I was rdanieg. The phaonmneal pweor of the hmuan mnid, aoccdrnig to rscheearch at Cmabrigde Uinervtisy, it dseno't mtaetr in what oerdr the ltteres in a word are, the olny iproamtnt tihng is that the frsit and last ltteer be in the rghit pclae.
The rset can be a taotl mses and you can still raed it whotuit a pboerlm. This is bcuseae the huamn mnid deos not raed ervey lteter by istlef, but the word as a wlohe. Azanmig huh? Yaeh and I awlyas tghuhot slpeling was ipmorantt!
If you can raed this forwrad it.
FORWARD ONLY IF YOU CAN READ IT.