It is narrated from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he said: "Whichever member of the Ummah of Muhammad (peace and blessings be upon him) sends blessings upon the sacred person of the Prophet (peace and blessings be upon him), or offers the gift of salam (peace) in his (peace and blessings be upon him) presence, those blessings and greetings are necessarily conveyed to him (peace and blessings be upon him), and it is said (by an angel) thus: 'So-and-so sends blessings upon you, and so-and-so sends greetings of peace upon you.'"
The chain of this athar (report) contains Abu Yahya al-Qattat al-Kufi, a da'if (weak) narrator; however, the subject of blessings and greetings being conveyed to him (peace and blessings be upon him) through angels is established by other sahih hadith.
Hadith Referenceالمطالب العالية بزوائد المسانيد الثمانية / كتاب الأذكار والدعوات / 3333
Hadith Gradingمحدثین:إسناده ضعيف
Hadith Takhrij«حکم الحدیث المطالب العالیہ محققاً تنسیق د. سعد بن ناصر بن عبد العزيز الشَّثري- مکتبہ شاملہ :هذا الإسناد ضعيف فيه أبو يحيى القَتَّات لين الحديث. » «انفرد به المصنف من هذا الطريق»