Manual for Gifts? Or just proper etiquette?

I think I have a manual for gift giving . But at the same time, I want to keep it. Is it bad to keep a manual?

I’ve been sending my clients personalized gifts (example could be a coffee mug or calendar that is personalized for them). I mail this to their address. I haven’t been getting thanked the last few times (to clarify, it’s a different client each time- not the same one). Anyway, weeks will go by and so I finally will reach out asking if they received the gift. They all did and just “forgot” to mention it.

I don’t expect a giant thank you. But bare minimum would be simply acknowledging it was received. It’s not difficult to send a 20 second text message.

So, all that to say- I don’t want to send these gifts anymore. Not due to cost per se as they are usually inexpensive. But it’s my time I take to personalize the gifts and if they aren’t even acknowledged, I don’t believe it’s worth my time.

C- Gift mailed to client(s) and no confirmation of receipt.
T- Hmm. Well, that’s rude.
F- Annoyed
A- Ask them if they received the gift I mailed
R- get confirmation that they did which confirms they were rude/lacking basic manners.

I know my R line is very judgmental. But c’mon! Even my 2 year old knows to say Thank You. And she does so without my prompting. It’s very simple.