That title is both ironic and a tad oxymoronic: it's not like I have an old favorite rejection letter, and I've never received a rejection letter I like as well as any of the acceptances I've gotten. Still, some rejections are less vile and upsetting than others. Here's one I got last week that doesn't make me want to give up not merely sending my work out, but writing poetry altogether:
Apologies for the delayed response! I really enjoyed "Portrait of a Bedtime Storyteller" but got a bit lost toward the middle. The ending is magnificent, though. Would love to see more of your work.
Apologies are indeed in order for the delayed response: this journal had my submission for NINE MONTHS. It's not at all unheard of for literary journals to hold your work for six months to a year before they get back to you, and that long response time is one reason journals that don't accept simultaneous submissions totally SUCK the putrefied body parts of long dead farm animals. This journal at least allows simultaneous submissions, so the poems they held practically forever were also seen by other journals, one of which is now going on ten months for its response time.
But at least the editor liked my work and want to see more. So one of these days I'll send more out.